I was originally planning on making a sock puppet account to post this review.
I'm still not happy with the series, in light of the finale. However, instead of complaining about the problems, I will present a solution.
Since Bryke, especially with the last two books, wanted to emphasize more political conflicts. I'd make things more realistic. The Avatar's decisions will not always be popular, however an unpopular decision isn't necessarily a bad one.
Here are my complaints and how I'd like to see them addressed:
One point is that Korra, while she has matured, isn't a particularly wise Avatar . Though she isn't necessarily a failed one. Korra's inaction (whether voluntary or otherwise) has led the world to adapt without the Avatar's presence.
B1 While Korra stopped Amon, she wasn't a part of the process to elect Raiko.
B2 While Korra defeated Unavaatu and left the spirit portals open, she wasn't a part of republic city's infrastructure being rebuilt. Nor was she concerned about the other nations reacting to harmonic convergence.
B3 Korra was sick and the air-nomads had to take over.
B4 Republic city is in ruins, a new spirit portal is unlocked. The Earth Kingdom's government needs to be rebuilt from the bottom up. Korra has just gotten past her three year rehab, and decides to go on vacation.
Compare Korra to the anti-Bush complaints when he flew over Katrina, or when he remained at the elementary school during 9-11. Or the "Obama golfs/vacations too much" or him saying he found out about the conflicts of his administration through news sources from CNN, and not the white house. Most of Korra's in-story opponents came off as more flippant (Toph, Raiko, her "approval ratings", etc) or evil (Unalaq, Amon, the Red Lotus, Kuvira). None of them were rational, though they could have been.
The biggest missed plot point, in light of Korra's inaction, was her preference of republic city. In her defense, it could be argued that republic city represents the four nations, therefore she only needs to concern herself with that place. On the other hand, the Earth Kingdom was being ruled by a despot, we don't see the fire nation, and apparently the Southern Water tribe is more advanced than the North.
Should Korra be concerned about these issues? The answer shouldn't be clear. But the question should be asked.