It seems as if you could get a lot more out of them instead of just simple rooms. You could live in a cabin, on the beach, etc..
Plus, it seems like you could get A LOT more people in a smaller space. I'd imagine you could save a tremendous amount of room as holodecks can house several people at once in a fairly limited space.
I understand it probably uses a lot more resources, but surely the pros outweigh the cons, right?
It isn't because of power. If the crew's quarters were decorated with holodeck technology, the hologram would only be generated while the crewman is actually using his quarters.
If the crewman was on duty, asleep, or if the crew went to battle stations, the hologram would be shut down. And this wouldn't result in people living in closets, because while at battlestations, crewmen are at battlestations - not their quarters. A crewman would generally never notice when it is shut down.
The ship's computer had the spare cpu cycles to create and run an entire sentient being in Moriarty. Hundreds of static 'cabins on a beach' quarters are even a drop in the bucket by comparison.
So here is my answer: Holodecks are simply too new.
Holodecks are a relatively new technology. Starfleet simply hasn't had enough time to integrate them into the basic design of a starship.
We don't know exactly when they started to be installed into starships, but we can be fairly certain it was after the between the end of the TOS movies and the start of TNG. That means at some point between 2293 and 2364. I'd be willing to venture that it is far closer to 2364 than 2293.
The system is very much riddled with bugs. In just a couple of years on TNG the holodeck nearly destroyed the ship half a dozen times. That isn't a technology that has seen widespread use for 70+ years. It is possible that the Galaxy class is the first ship to be fitted with the holodeck, at all.
In a modern day military, hulls are designed to last 50+ years. The Excelsior class was in service for over 100 years.
I don't think there would be too much impetus to retrofit older models with holodeck quarters. The main advantages to ship design (making quarters smaller) couldn't really be achieved with a retrofit. What you are proposing would only even be considered after the holodeck is a well proven technology and all the bugs and kinks are worked out.
So perhaps 50 years after holodecks are introduced and they are drawing up plans for a new ship class, they'll throw in holodecks. Unfortunately that time won't be 50-150 years after the end of Voyager.
Holodecks draw a lot of power. Anytime you had a need for shields or weapons you would likely be distrupting the Holodeck environments. It is a lot more energy efficient to have non-holographic beds and rooms for crewmen.
Additionally, even though it may seem like you are in a wide open field with a cabin, in reality there is a finite amount of space inside that room. If you had a lot of people in the room, eventually the Holodeck would be unable to hide everyone from your line of sight, or sound.
There is also something to be said for the privacy of intimate coupling.
In addition to the other, more technical answers : I don't think people would want to give up the feeling of, no matter how limited, having a home out there.
Coming home to your quarters, with pictures you or a loved one may have painted, a printed book you treasure made of real paper, an ancient musical instrument you play, in short with real things is something to ground you, even in outer space.
The holodeck is a wonderful toy, but not something to come home to and be at ease and relax and go to sleep in.
The personal touches you add to your quarters are real and therefore really personal; the unlimited possibilities of creating illusions simply can't replace this reality.
The reality of objects can't be fully replaced by holo-objects. Data doesn't feel the difference (yet?), but Picard feels the value of touching the 'real thing'..
My initial thought would be that it would be energy and computing resource intensive.
On top of that, even if you had excess capacity of those resources, during an emergency or power loss, everything would crash to the ground and people would be stuck living in dismal closets.
I agree with User51311 in that the power necessary to maintain a holographic crew quarters would be a huge waste of a starship's resources. Having physical living quarters would not put an strain on ship's reserves. I'd reference the third act of the episode "booby trap". The Enterprise is running out of energy, and "the programs running unnecessary energy are terminated, including the holodeck program Geordi is running"
https://memory-alpha.fandom.com/wiki/Booby_Trap_%28episode%29
I would also like to point out that you could NOT get a lot more people into a smaller space in the holodeck. The room has a physical size. Take a look at this previous question
How does holodeck keep people from running into the walls?
When people move around in the holodeck the illusion of size is created, but the room is always the same size. You couldn't put but so many people in the holodeck before you'd be hitting the walls.
Holodecks are a form of entertainment, relaxation and escapism:
TNG:
TROI: You know, I don't spend nearly enough time on the holodeck. I should take my own advice and go there to relax. Next time I'll choose the programme. If you like the Black Sea, you're going to love Lake Cataria on Betazed.
VOY:
DOCTOR to JANEWAY: I've checked Starfleet regulations. The Chief Medical Officer outranks the Captain in health matters. Now I realise this may be the first time a hologram has given an order to a captain, but I'm ordering you to report to the holodeck, now.
But holodecks are also a distraction:
VOY:
JANEWAY: It seems to me that people have been getting a little too comfortable around here lately. They're late for their duty shifts, taking mess hall privileges during non-designated hours. And a lot of people are spending more time on the holodeck than they are at their posts. You are Security chief. Don't thirteen department heads report to you every day?
VOY:
DOCTOR: I see. I realise your Sickbay training is purely voluntary, but you haven't spent any time there in several weeks. And when I try to find you, you're always in the holodeck. PARIS: Correct me if I'm wrong, Doc, but we haven't been treating anything more serious than an ingrown toenail. DOCTOR: That's beside the point. If an emergency were to happen you must be prepared. You're too far behind in your medical texts to be wasting your time in the holodeck.
Restricting holodeck time is thus a tool for crew discipline:
VOY:
CHAKOTAY: You're not doing anything against Annorax. That's an order. PARIS: What are you going to do, take away my holodeck privileges?
VOY:
DOCTOR: If I weren't your only doctor, I imagine you'd confine me to the brig. Confiscating my emitter would be an equivalent to punishment. JANEWAY: I'm not sure that's appropriate. DOCTOR: If that's not enough, you can take away my holodeck privileges. And my autonomy protocols.
Holodecks are the main form of recreation on the TNG / VOY ships. Their use is rationed, as too much use distracts crew members from their duties. Putting a holodeck in everyone's quarters where use is uncontrolled could therefore cause a problem. Furthermore, it would take away a tool for enforcing crew discipline.
I think one of the big answers to many "why don't they just..." questions with Star Trek is it would take the crew's experience too far from our standard experiences.
In order to keep the characters grounded to a level typical viewers can identify with, almost everyone on the main shows are human. Those who aren't human are constantly striving to be more human (or struggling with some mythical "human half", as if a person can only be one race or the other). They constantly make references to people and literature modern people have at least heard of. The social and political struggles reflect those of the viewers' presumed experience. The writers constantly find ways to make sure genetic engineering, cybernetic modification, or other post human ideas can only make it into the show for short stints, or in small doses.
In this case, if the crew members had holodecks for bedrooms as a normal thing, it would create too much disparity from this our-Earth-on-a-spaceship mentality.
Plus, it seems like you could get A LOT more people in a smaller space. I'd imagine you could save a tremendous amount of room as holodecks can house several people at once in a fairly limited space.
I don't think so. Holodecks aren't just the walls. They also require power systems, computer systems, and other support infrastructure. By the time you account for all of that, the expense and mass of a 10-man holodeck is probably at least as much as 10 normal crew quarters, if not far higher. You might take a little less volume with the holodecks, but by the time holodecks are in play space is obviously not at a premium. Otherwise, they'd be sleeping with 10-20 people in each of those giant crew cabins, hotbunking, etc.
