Originally Posted by PunkFunkDunk
Short answer: because they are ugly. Or, more accurately, what we here in Australia call fugly (fat + ugly).
Huh! Among professional architects this term also means "functionally ugly" and is used to describe the more horrible examples of Brutalist architecture from the 1960s to the 1990s.
I've said "fugly" in passing to friends in Melbourne and had some odd looks. I now know why...