A prayer is surrounded by the mercy of Allah from two sides; by success ( tawfiq) from Allah, and by the response ( istijabah) from Him. Basically, a servant cannot engage himself in supplication without the tawfiq from Allah. Such a facilitation by Allah is necessary before supplication.Why do you pray to Allah?
Replace God with Allah - that's just the name we give God, and so we pray to him as acknowledgement that he is the supreme, most benevolent and ever-present. He is the owner of the Day of Judgement, the ultimate creator and ruler. Belief in Allah is the basic tenet of Islam.