Finally somebody who managed to put my "vibes" from watching that show into a succinct statement.

Aang didn't want to be the hero but it was forced on him. Korra was chomping at the bit to be the Avatar, right? Finally gets it, and is overwhelmed by suddenly being solely responsible for fixing things that are way beyond her control and understanding. Then Forrest Gumps her way through mistake after mistake for the rest of the series...