Yeah, I can see not having tooltips until a final/near final release. On the flip-side though, a general description of what each building does would be nice. Just, like, entries in the Xenopedia or something. One thing I do hope though, when they add tooltips, is that you'll get info about what that specific structure is doing, and not just info about the type in general. Like "Lab 2 >> 3 active scientists >> Researching: Alien Invasion >> 40% complete, 36 hours remaining"
Also this is way too nit-picky to warrant it's own thread or anything, but I think it'd be great if you could click on a structure to go straight to the tab for what that structure does (Clicking in an occupied hangar takes you straight to the screen for that plane, etc...)