It seems to me that if you look down and see 22 preflop, it's not much different than seeing 66/77. The reason is that if you don't catch a set (In which case you'll most likely win either way), you probably don't have an over pair. In the unlikely case that you end up with a flush, 7 high isn't much more powerful than 2 high.

Can anyone give me any reason to raise preflop w/ 77 but not w/ 22?