What is so horrible with the idea that God obeys man?
Didn't God obey man when man condemned him to die? And why did God obey man? Becasue God had given man the power to sentence Him to death. Had God not given man that power, Jesus could never have been crucified. "You would have no power over me if it had not been given to you from above" says Jesus to the man who condemned him to death.
If God has given the priest the power to consecrate bread and wine--that is--to transform them into His body and blood--how is this "worse than you thought?" The priest is only doing it becasue God wills it.