- I think it boils down to priorities.
- Even the SGC appears to care less and less about exploration as time goes by.
- Asgard, and likely other advanced races, dont care.
- Goa'uld are too busy infighting and "doing things the way they have always done"
- Such a list would be pointless without a followup search to see if it is a useful address as well.
- Also I would argue that it is not possible...
So, priorities come into play quite a bit here. When the SGC first starts its exploration they care quite a bit about finding everything they can; but as the story progresses there are more and more episodes where we see SG1 on some specific mission and exploring less and less. I did a really quick scan of the seasons on wiki, and as you would expect, as the seasons progress there are less and less "exploration" episodes and more are keyed to progressing the story line or us needing to revisit something/someplace we already have before. Below I have a quick list of the seasons and how many episodes within that are purely exploration based:
- Season 1 - 13
- Season 2 - 10
- Season 3 - 11?
- Season 4 - 8
- Season 5 - 5?
- Season 6 - 4?
- Season 7 - 5?
- Season 8 - 3
- Season 9 - 1?
- Season 10 - 1?
I relate this because as Earth gains more and more influence in the galaxy and more and more pressing matters arise, SG1 is less and less concerned about the SGCs mandate.
Considering the short time compared to other advanced species in the series, everyone else has gotten past the "honeymoon" phase of the Stargate network long ago. Even if they all cared to search the network for available planets way back in the day, they are beyond that now.
The Asgard were much more concerned with the replicators to find new planets; and I suspect resources would have been the only benefit to finding something new. Plus they had their own galaxy of gates I would assume!
The Nox, Tollan, etc. I expect to all have been happy with their little corners of the universe carved out.
The G-men were also extremely busy with both infighting and the SGC screwing everything up all the time to really care about what else is out there. Sure, when a situation arises that they can take advantage, but they are not necessarily looking for it. Anubis only knew stuff because of his unique situation and I think there were only a handful of other occurrences of them thinking outside the box.
That said however, it is possible that someone was trying to find them all for whatever reason. The G-Men do not always disclose with one another their plans and research; so it is possible someone was, but never disclosed it. Also we have seen that some Asgard do their own thing (Loki cloning Jack for example) and maybe there was some rogue scientist that was doing that research.
But even if someone was making a list, what good would that really do? Even if you wrote a program that looked for all possible connections to gates in the system you would not only just have a big list of possible doorways you probably will never go through, but you have also just taken your gate out of the system as well. If you are busy dialing out to a random planet... you can't dial out and no one can dial in.
But you also have to consider the gates that are in network, but inaccessible. A situation similar to my favorite episode Season 4, Episode 6 "Window of Opportunity" could arise where a gate is even temporarily out of network at the moment you try to connect and you cross it off your list thinking it is destroyed or non-existant.
Another troubling situation you might need to be prepared for is Season 2, Episode 15 "A Matter of Time" where you gate into a black hole and can not break connection. Is your phone book worth that risk?
And the sheer amount of gates in the network might make this a life's work. I direct you to this related answer: Is there any indicator as to how many planets have Stargates?
I understood from that episode that at the start of the update it would take two hours maximum; but even still that is a bunch of gates. (Which also begs the question, how would buried gates get the update if a connection can not be made? Season 3, Episode 19 "New Ground" is such a situation. Without the update that gate must have been close enough for drift to have not come into effect I guess... once you have had a gate buried long enough would it even be possible to connect anymore?)