The two questions that I find myself asking with regards to buildings are "How long should a building last?" and "When is a building requirement meaningful?"
I think most buildings should be part of some kind of upgrade path unless there's a solid reason not to. I prefer upgrades over direct obsoleting because that doesn't slam the player in the face. You still benefit from the old building until you get around to building the new one. I also don't think most buildings pre-Renaissance should be sticking around all the way to the end game. In BTS, most buildings are one-and-done, but I think AND can push that.
I've managed to weed out most of the buildings from the Ancient/Classical/Medieval eras that weren't part of some kind of upgrade chain. Religious buildings and civic buildings I can leave alone. Civic buildings are tied up with their civic, so as you switch to more advanced civics, the older civic buildings go effectively obsolete and if you don't switch, then you don't get the new civic buildings. There are a couple changes I do want to make.
- Brothel: Obsolete with Androids. From a purely mechanical standpoint, this knocks off a point of Happiness that is unnecessary with the presence of so many other happiness sources.
- Jewellery: This should be part of the Omnifactory chain as well. Currently, the Omnifactory provides +50% commerce, upgrading +10% each from Nanofactory and Oil Refinery and an additional +5-17 depending on resources from Textile Mill. I think rolling in Jewellery's +10% gold and +3-7 commerce from resources should be okay, and if anyone can show a commerce drop, Omnifactory's commerce can be pushed up.
After that, the only other pre-Renaissance/non-religious/non-civic building left standing is the
Courthouse.
As far as meaningful requirements go, once I start seeing a gap of over an era between the prerequisite building and the thing it unlocks, then I start to think that the requirement isn't enough of a hindrance. For example, the
Biological Warfare Lab is available early in the Modern Era. The
Plague Bringer comes late in the Transhuman Era. That's a big enough gap that for this particular unit that I think a new building should be necessary -- thus the idea for the
Gengineer. I see the same gap with the
Zoo being a requirement for
Dinosaur Park. Zoo is mid-Industrial; that's two eras difference. I can make exceptions if there is an additional risk: for example, the
Warhead Factory comes with a nuclear meltdown chance. That's significant enough that I don't think we need an additional building for Transhuman nukes like the
Peace Maker.
per 10% 
