That is Petra doing it, it's not inherent to the game. It makes the AI "stronger" but arguably "less fun" to play against. So if there is some consensus we could revert it. 

Yes, I agree, since surely these posts in Cyrillic are a first one. I'd maybe even go further and require mod approval for the first three posts, since I seem to remember someone posting something that made sense and then their second post was total spam.

It also works when the building is finished, because 100% built means 0% of resources back, so that works as a general rule

Exactly. In SP at least, all buildings being destroyed once the CC has been captured is oindee a pity 

Alright, but definitely not when the building is finished. Destroy after use will not brign back any resources? Too bad.