Fred, I too dislike the "You know, it's not just about you" business. You touch on several issues, but on the subject of catch-phrases I'll say this: I feel that American culture has been dumbed down considerably over the past couple decades. Some other cultures may have experienced this as well--I suspect so. This reminds me of learning a foreign language. We are given everyday phrases to learn. Hola! Como esta? Bien, gracias. (There's probably an upside-down question mark available somewhere.) Useful for learning a new language, but I feel that much conversation gets reduced to these catch-phrases. And when someone is angry what comes out? A catch-phrase (or foul language). When we're feeling rattled we're often inarticulate. It is used as ammunition.
I feel that your words on self-interest are more than fair; we are all, of course, motivated by self-interest. When I hear the phrase it isn't really about the words--it's just another form of rebuttal.