If you play a game with the mindset that you are controlling the cursor, then up should be up and inverted controls would make no sense. However, if you are playing a game with the mindset that you are contolling the character, then an inverted y-axis is clearly more logical.
Lean forward right now and tell me what happens. Now lean back. As you can see, a forward motion is associated with looking down while a backward motion is associated with looking up.
Inverted is much more intuitive and should be considered "normal."