Why is the ship's computer not advanced enough to insert the stardate automatically when a new log entry is added by the captain? Or is there a special reason for it not to do so?
It's simple: Logs aren't recorded in real time.
During a tense space battle, the Captain can't just take a break to record the fact that someone just attacked his ship, he will remember it and when it happened and then write it down later with the stardate of when it happened, and even the advanced computers of star trek won't be able to remember automatically when the events described happened, or the computer would write the logs itself.
It seems to be part of Starfleet protocol to start each new main log entry by saying the Stardate aloud. Presumably this is in case the log itself is damaged and only a part of the recording (the audio portion) survives or in case there's an attempt to selectively edit the recording.
You can see the value of this in the episode TOS : Court Martial where a crewman falsifies a visual bridge recording. Had there also been an audio component, it would have been twice as difficult to create an edited version.
Note that this procedure is also carried out in the real world in formal police interviews and when taping autopsy reports.
There may also be a need to tell the computer in what order to place a log entry. On several occasions (in TOS : By Any Other Name, for example) it's clear that an entry has been created retrospectively. In that particular instance, Kirk creates an entry talking about a trap that he's set for the villains that he's sitting next to:
Kirk : Captain's log, stardate 4658.9. With The Enterprise under control of the Kelvans, we are approaching the energy barrier at the edge of our galaxy. Spock and Scotty have devised a suicide plan to stop the Kelvans. They have rigged the ship to explode on my signal.
Just as current ships keep a log of events that are based upon time, so too are personal and ships' logs maintained in Star Trek. Modern ships, especially larger ones, have Ship, Deck, Weather, Officer's, Maintenance, Engineer's, Flight Ops (for carriers), and other official logs. With all those official logs that a crewmember might be making entries into, it's quite natural that personal logs would reflect this habit as well. And, given that Gene Roddenberry saw StarFleet as an outgrowth of the modern Navy, he sprinkled Star Trek with this and other Navy-isms.
First of all, I'm sure it is advanced enough but we do lots of things in real life for historical reasons that have no reason to continue other than we like to do it that way. Starfleet probably has a policy that all log entries will begin that way, and who wants to argue. I'm sure if you look at the files there's a timestamp next to the file; many of which will not match the stardate mentioned in the log entry.
What policies are in place at your work that are silly, but you keep doing them because that's the way the old school boss likes it?
Most everyone here has argued from a functional perspective, but personally I have a non-functional reason.
Tradition. Starfleet isn't primarily military, but they still have a lot of military trappings and they definitely borrow from various naval traditions, like the use of a bosun's whistle (Admiral Kirk is greeted with a boson's whistle when he boards ship in Wrath of Kahn).
Ships logs have always started with the date, ergo to the military (or pseudo-military) they always will.
The character doesn't necessary have to have uttered the words "Captain's log. Stardate..." while dictating in universe. Generally what we are hearing is a voice-over reading of the completed journal entry in the captain's voice. This reading is part of the movie (TV show), not of the events depicted.
Since it is not part of the on screen action, I don't think it requires an in universe explanation. Whether the film was shot in universe or out, the words were read by the captain at the request of the cinematographer.
Are their scenes were the captain dictats these words on camera? If so, there are are possible in-universe explanations for this too.
The "Captain's log" occurs in the earliest episodes of the original series (1960s). At its introduction, it was likely not conceived as a function of the ship's computer, but something more like a simple audio recording (think 1960s audio tape recorder). As such, there would be no automatic date stamping or computer processing of the log. As the original series progressed, the computer and its characteristics gained definition and also capability, but this was after the format of the log had already been established.
The Next Generation introduced a much more sophisticated computer, making the original-series-style logs anachronistic, but the format and style of the "Captain's log" was a hallmark of the Star Trek franchise.
With our 21st century perspective on computer technology, we can look back on the original series and imagine that such a "Captain's log" as depicted in TOS won't make any sense at all by the real 23rd century.
Bottom line: as already stated in other answers, there is no coherent in-universe explanation; you have to step out of it and consider the time in which Star Trek first went on the air, and the storytelling style which Roddenberry chose for the show.
In-universe reality would have no need to record "Crewperson's log, stardate _____". The computer will handle all of that. Concerns of the date being recoverable if other data are lost, or matching dates up are laughable. Do you think there's a cassette recorder behind the console? Police/autopsy reports speak the date and details because there IS a cassette recorder attached to the microphone, I don't see Starfleet regressing that many centuries.
On this site, do you explicitly write the date and your username in each edit box? Of course not. Stackexchange's server takes care of those details.
The log entries are purely a narrative device to explain things to the audience. Don't forget it is just a TV series.
I don't understand the question. The computer on Star Trek DOES automatically prefix every log entry with the name and rank of the person making the log entry and the date on which they made it. The person doesn't say these things, they just add the narrative. Of course the computer adds this information using a synthesized voice that duplicates the exact voice patterns of the person making the log entry. :-)
Seriously: Arguably, in "real life" the computer could attach to all recorded log entries the name and title of the person making the log, the date, perhaps other information. So when someone played the log, they would hear the computer voice say, "Captain's log, star date 3249.2", and then the person's voice saying the rest of the log entry.
But this would have been broken the flow of the introduction to each episode on the TV show, hearing one voice say the person and date and then another give the narrative. Even if the producers thought of doing that, they might have rejected the idea as cumbersome. Viewers might be confused by two different voices. Would all viewers instantly and automatically realize that this was supposed to be the computer attaching "context" information to the log entry? Or would they have to explain it? As this device was used at the beginning of each episode, that could mean they would have to start each episode with an explanation of how log entries are made, which would get dull very fast for regular viewers. I suspect that even if the producers thought about it, they just dismissed the idea as not worth the trouble of dealing with.
In-universe explanation: Even though the computer will automatically record the date and time and possibly other relevant information like location and ship status, there is still a good reason for the person making the log to state the date. It shows that the person is aware of the date and can be seen as a formality to establish that the person is of sound mind.
Metacontexual explanation: Clearly, the original Star Trek series was in a time of tape recorders when automatic time stamping just wasn't a thing, so they went with an approach that gave an impression of a military with protocols. The explanation above is a retrofit to make the tradition of the show make sense.
Computers in Star Trek often interacted with via verbal commands. Who can forget Scotty's "Hello Computer".
Despite the computer in TNG being sophisticated enough to create sentient beings, it is more like a tool. The computer mainly responds to crew members. It doesn't make it's own decisions, it doesn't question crew members, all it initiates are warnings on the console. With this in mind, it makes sense that a crew member commands the computer to make a log entry for a particular date.
- Many of the admirals back at Star Fleet HQ are old enough to remember when CAPITAL LETTERS ON THE INTERNET WERE CONSIDERED SHOUTING. Reading a log on the screen in Star Fleet font makes their eyes bleed so they instead prefer the audio replay, which, naturally, requires the star date to be read aloud.
Think about the Star Trek universe. All sorts of weird unexpected things happen that screw with the minds of the crew and with the computer. (Time travel is one pertinent example.)
For a third party to understand a chain of events, the chronological accuracy of a log (or any account of events) is necessary (or at least, very useful).
Given the two foregoing points, you wouldn't want the chronological accuracy of the log to depend on just the state of the logger or just on the state of the computer. Accordingly, it makes sense to have the logger enter the date, despite the fact that the computer records the time when the logger logs the entry.
It's not by design -
Star Trek, as visionary as it was, was created in a time that was almost 100% analog. To call someone, you had to memorize their phone number, or look it up, and then manually dial out, on a rotary phone, each of the numbers. If you got a busy signal (no voicemail, no answering machines, even), then you'd have to remember the number, again, and dial it out (no stored phone numbers or auto-redial on rotary phones).
If I wanted to see an newscast from a date, either the person reciting the news would mention the date, they'd have to film a card with that information, or the storage canister or date would have to be logged or written on in some way. When people kept diaries, each entry would be marked with the date.
A captain's log is an audio diary entry, basically.
If you wanted to remember when a photo was taken, you flipped the physical photograph (no online storage or digital images) and wrote the date on the back of it.
Probably, they simply did not think outside the box enough to imagine the date and/or time being captured without intentionally notating it in some way.
Since this original process was set as the standard in that way, future versions of the show just kept that tradition for the sake of continuity with what was already established.