I think the passive aggressive solutions exist because most people have terrible communication skills. It seems like it all comes from the assumption that if you actually disagree with someone or want them to behave a different way around you, you must be a huge asshole that no one will respect. If we communicate indirectly, we get to claim the higher moral ground because we were merely "passive" while the other person OBVIOUSLY didn't get our EXTREMELY OBVIOUS indirect message and therefore must be not only an asshole but an idiot.

Now the other guy is the rude idiot. Problem solved!