Remember when Lightning Bending and Metal Bending were special skills that required you to have the right personality, affinity, and mindset to be able to achieve? Or that Toph was cool and fancy because her metal bending came from her unique circumstances?
Or how we've been shown that letting the Spirit World actively mix with the human world is a bad idea because the last time it happened, humanity was forced to live on giant dragon turtle things?
Pepperidge Farms remembers.
The writers of Korra, not really so. No, it is clearly the city at fault for calling Korra out for the negative consequences of her actions that caused death and strife. Remember that airship Vatu shot out of the air? Yeah. That did *not* crash without casualties. At least the Air Benders coming back could be more easily explained as Harmonic Convergence reactivating inherent Air Nomad genetics and abilities that were likely either hidden and/or forgotten over the years to avoid persecution.
Amon 2.0 or whatever that Book 3 antagonist was called should totally have been an Earth Bender, though. Locking him up in max security despite being a non-bender's weird. Speaking of Amon, he should've just been a non-bender, would've made it more interesting in my eyes.