1- When you make a pure mage character(magic schools + enchanting) your character becomes highly overpowered, but when you make a pure warrior(combat schools + smithing) your character is still pure sh** on Master and the most cretin dragon can kill you with a couple of bites or a single shout. You would need potions of resistance/health to do that, which would break the concept of a pure warrior.
2- Every dragon priest became a dragon priest due to their magical abilities.
2- All the most powerful and hard to kill NPCs are mages. I can beat a pack of 50 warriors with a mage, the same can never be done with a warrior, or agaist 50 wizzards as they all one-hit you.
3- The dominant races of Tamriel are natural mages, such as the Altmer and the Dunmer.
So truth be told, mages are clearly superior to warriors.