Uhm the narrative of book 3 frames Unalaq as the jerk for betraying the Red Lotus and following own plans, but honestly, replacing what to him is a bad avatar by a new one thinking he’ll do a better job sounds to me like a much better plan than “CHAOS YAY! Let’s leave people to do what they want” The inital Red Lotus plan sounds more in line with Vaatu than Unalaqs idea of spirits and humans living in harmony (Maybe he should’ve allied with a different spirit).
I mean if Vaatu were not a malicious spirit Unalaq being a new Avatar could’ve gone well, if Vaatu were good natured he could’ve prevented Unalaq from causing harm even if he were out for power.
Problem is just that Vaatu’s a big troll.
All antagonists so far had that “the avatar must be destroyed” goal, but the first two wanted to replace the Avatar.
I think the Red Lotus wanting to end the Avatar was both as a motivation and as a plot rather weak. When it comes to destroying the Avatar book 2 did a better job at handling it and together with Korra understanding she is more than the Avatar it would’ve been a good conclusion for the end of the show or book 1 if they had only one season.
I mean imagine the final confrontation between Korra and Amon would’ve been him severing her connection to Raava/taking her bending away(it’s technically the same since it’s in both case removing her being the Avatar what she defined herself as til this point) and then her understanding she’s more than that and doesn’t need her bending/being the Avatar and then defeat him.
Like I don’t know, make the show one longer season(26 eps? okay maybe a bit more)
Keep Amon as the main antagonist, make him actually spiritual like Unalaq, start with what we’ve already seen and introduce his debending ability by taking out the triads, add the new airbenders plot maybe in the middle due to opening the portals or some other way of letting spirits in through Amon(at this point the nonbender conflict would have to go with the new airbenders in some way and it’d be clear Amon has fucked up, but unintentionally, general development on the topic that one is more than their bending, reactions of nonbenders becoming benders, even refusing it also here’s some room for Noatak to get along with himself)
Have harmonic convergence as the finale (as in korra didn’t manage to close the portals in time or they didn’t know about it and just tried to get along with the spirits) and a group effort like the book 3 finale be what defeats the enemy(Amon being upstaged by Vaatu? cause he didn’t expect he’d release this kind of threat and fucking things double up because he removed Korras bending before, which also prevented her from closing the portal in time, or Unalaq enters the stage as mr spirit expert being backstabbed by vaatu and Amon goes in the time out corner to think about what he has done, cause after taking away Korras bending and opening the spirit portals showing not to be such a good decision his job is done, maybe he can contribute something at the end to redeem himself).
I dunno or even that Amon hadn’t anything to do with the spirits and Unalaq was already orchestrating things in the background and when he saw that impostor pretending he’s sent by the spirits Unalaq being the one opening the portals because he wanted to teach that impostor and that half baked Avatar a lesson while gettin rid of both of them becoming the new avatar.