I'd actually argue that prayers aren't selfish begging, but selfish bragging. They are a way for a person to go "God, look how much I care about other people. Aren't I a great person?" Anyone who honestly believes that some deity has a "perfect plan", and yet prays to that god as though to change the outcome, can only possibly be either trying to get that deity to change away from perfection, or to demonstrate their own "caringness".
But then, this is like those christians who proclaim that morals come from god, and thus atheists have no morals... when in fact, an atheist does good things because it's the right thing to do, while a christian who believes that morals come from god does it because they're told to. (of course, there's also the sensible christian, who simply believes that god taught the morals, not that he made the morals - such a christian is quite fine with me).