I´m not sure how these kitchen units for sinks are actually build in your part of the world. But most manufacturs here in Denmark, actually removes the entire top plate, and replace it by a thin metal piece in the front, to keep the unit stable... So I just need to make sure that a 3" sink, won´t be placed in a 2" Unit (Which I would never do in real life either)
Basicly, I try to model and plan my families, to suit the "real" world counterparts.
Now, if in real life, you would get out the jigsaw, and cut a hole in the top plate in the unit, I totally get your point ! But maybe, you should adopt my way anyhow