Because there is a cause

"Rock stars are performing to raise money and awareness for a cause."

That cause being inflation of their already overblown egos? I can't quite get a handle on how that is admirable. And can you explain to me how awareness feeds hungry people or facilitates world peace? That's one of those style-over-substance things. Awareness in this context is a nifty, feel-good word that is utterly content-free.

"The actor is playing the role of president."

If that was nothing but playing the role, I hope we find someone who can do it as well one of these days. If that was nothing more than playing the role, Carter's entire term would have to be described as a bad case of catalepsy. Of course, Carter meant well, didn't he?