Surely praying is about more than simply demanding shit? I assumed praying was based around giving thanks?. In all honesty, if I saw some conclusive proof that a benevolent almighty being had created us, and had been watching over us, I would probably go with 'thank you' before I went with 'I want a new bike'.
As for the 'God has some flawless plan for the world, trust him to do what's best for everyone' crap;
"Is God willing to prevent evil, but not able? Then he is not omnipotent. Is he able, but not willing? Then he is malevolent. Is he both able and willing? Then whence cometh evil? Is he neither able nor willing? Then why call him God?" - Epicurus
God might exist, but to assume that we can sit back, do nothing and let God take care of everything is baffling.
Essentially, you, just like people from all cultures around the world, back to stone age times pray to God because you feel alone in a confusing and uncaring world. The idea that there is an all powerful being protecting you, and who cares about you, lets you get on with life, instead of being paralysed by the fear of the nothingness that awaits you after death. THAT is the reason to pray.