Specifically, the fact that buildings change size as you go up ever few levels. If I wanted to grow a new (elven) L31 residence (4x4), it isn't enough to find a 4x4 space for it because I have to deal with the 5x3 size that residences are between L24-27. Other buildings undergo even more extreme gyrations.
Since space management and dealing with odd and ever changing building shapes is one of the core elements of the game, I can't even see them letting you bypass this. [Maybe, maybe an option to do multiple upgrades where every new level is the same size: So given a L23 4x3 residence, you could upgrade directly to L27 (placing it into a 5x3 hole during upgrade). When it's done, do another upgrade to L31 (in a 4x4 spot). But the build times are long enough that I don't see a lot of value in batching four 18h upgrades into a single 72h upgrade. And how often do you really build an entirely new building? Not that often in the grand scheme of things.]