From the Tiger Details list on Daring Fireball:

I can't stand seeing these insipid ".app" extensions everywhere, but I don't want to turn off the "Show all file extensions" preferences because I do want to see the rest of them.

Actually, I think this change toward consistency might be a good idea, if only in an effort to help protect people from trojan applications hiding as applications whose extensions would otherwise be hidden. But, seems like a place where a third-party app can step in for people who know what they're getting into.