Eh, that's true.. at least, when I've tried to crawl under some pipes it doesn't seem to work.. Mind you though, it must at least decrease its size a little bit, otherwise crouching behind objects wouldn't do much good.
I think the getting stuck and the pipes are just yet another example of Bethesda failing to produce satisfactory results in a final release. I still get vexed at the 'invisible walls' that stop me from making easily performed shortcuts. Or the fact that for some reason I can't jump while standing on certain cliffs all because I'm standing in some particular place.