This is a major issue with some of the older maps, and a lot of custom maps.
Since the PE came in (with buildings considerably larger than all other races), the need for larger starting areas became necessary. There are a good few maps that happen to have had this issue, and I'm sure that Relic fixed plenty of them, where the PE were completely unable to fit all of their buildings in their base area.
My point however is this: which maps have caused the issue? Surely it would be far easier to fix the base areas than adding a rotation mechanic?