I think that tipping encourages good service and fosters competition. You're not forced to tip if the service is awful, that's the point. I'm not too sure (my last trip to the US was when I was a single digit age), but I think their prices (and general cost of living) will reflect the fact that tipping is the norm, e.g. don't imagine UK/Irish prices + tip added on.
Tipping everyone in the world ever is a bit ridiculous though, re: the guidelines Dog-amoto's posted But that's just because the practice doesn't exist over here, I guess.