I'm with you on this one, but I've recently decided that "Hi Phil" boils down to some fundamental personality split rather than a misunderstanding; I don't think either side will soon change. I believe "Hi Phil" people are really just trying to be polite and minimize interruptions (or at least their magnitude), waiting for permission to really bother you, so to speak.
Whether that's true or not, I respond if I'm ready, or I ignore it and go on with my work if I'm in the middle of something, just like I would with a full question. The only difference is I'm not thinking about the question with my spare cycles in the mean time.
If someone is trying to inform me of something urgent with "Hi Drew" I think it's reasonable to say that's their own fault.