[Ali Imran]

do you ever wonder why the omnipotent Allah didn't communicate with Muhammad directly instead of sending him an angel? Come on he is omnipotent! Please do not say that it was the best approach to revealing Quran because it seems a very inconvenient, time consuming way that requires unnecessary resources. 

I like such questions.

Yes, Allah spoke to our prophet directly.

The Quran however is a revelation and it must be delivered by a powerful messenger with all the trims. 

If a king wants to deliver an edict to people, it is usually delivered by an elaborate messenger and bells and whistles.