It's called confirmation bias.
(1) If "god" already is aware of what you need, because "god" is all-knowing, then praying, to ask for a request or a favour, seems pointless. As he/she/it already (should) know(s). And, he/she/it has already decided the course of action/the fate, because if prayer moves him to action, then, see the second point.
(2) If one is praying to praise "god", to thank him/her/it, then it makes it seem like "god" is in need of praise. What does that say about their character? Their ego? Their arrogance?
(3) If praying to "god" is to enforce a personal relationship with him/her/it, then that's a very skewed definition of a relationship. You talk, he listens. Where's the give and take? The compromise?