[Note: Never finished the main quest of oblivion, always got bored with it after getting the last book] [And yet I finished Fallout 3's main quest. Go figure.]
The player makes more sense as an avatar of Akatosh than anyone else, not as a character who gained Akatosh's power temporarily, but him in human/elf/whatever form. You see the world from outside the world, have meta-knowledge of reality, can reverse time, see the future, single-handedly postpone or entirely prevent the Oblivion invasion (by avoiding Kvatch and the road south of it) which you deduce using meta-knowledge, cause enemies to shoot arrows and throw spells at completely the wrong location, completely missing you, and your character is effectively unkillable due to your ability to reverse time even after dying. The only reason you can't prevent the catastrophic loss of the Amulet of Kings is because the game doesn't give you the option to say "Dude. I can't be killed. That amulet is far safer with me."
Were it possible, I would have never given the amulet to Jauffre, would have become a vampire and then gone and drank some of Martin's blood to gain Septim blood myself, thus fulfilling the requirements for wearing the Amulet. Then I would have theoretically been able to end the Oblivion invasion myself.