mcl630: I'm having the same issue. I've installed it fresh from set_ftl_2.0.0.9.exe then applied the patch_faster_than_light_2.0.1.10.exe. It makes no difference if I let it install in the default location or if give it a custom location.
The executable itself (FTLGame.exe) is marked as requiring administrator, so I doubt there's anything we as users can do about it. The developers need to fix this. There's absolutely no reason a game should need admin (other than the installer obviously).
Or, you know, you can go to the file properties and unmark it.
It does not require to be run as administrator per se, though GOG may tick certain compatibility options to avoid as many problems as possible. Actually, plenty of GOG games act like this, I do not know why this particular example bothers you so much, but if you want, you can launch FTL without UAC prompting you.
mcl630: Some users prefer to deactivate UAC completly (like GOG support suggests)
Deactivating UAC is rarely a good idea, unless you know what you are doing. I've never seen GOG support suggest it as a permanent measure.