I've heard it explained that "hey" used to be more of an urgent way to get someone's attention, rather than a casual "hello" like it is now, so it sounded rude to some older folks.
I think it's a pretty good example of something that totally lost all meaning and got beat into the ground, rather than getting worked into some individual lexicon or accent, and having a specific kind of role.
Totally passing observation on top of that, but I think, it's probably much easier for that to happen to specific references, than for that to happen to actual novel uses of language.