It's hard to be concise about this but to me, the most annoying thing is the idea of "I believe it-and since I believe it, I'm right and you're not" kind of attitude. Dr. Camping, for example, could have said something like, "Here is why I believe the Rapture will come in 2012" and he could have said, "I was wrong" when the Rapture didn't happen.
Certainly I don't know the minds and hearts of those who make these predictions. If this is a wish for the Lord to return and complete the last phases of Bible prophecy, then I say, "Amen; even so, come Lord Jesus!"