
Very Unpopular Opinion: The avatar shouldn't have the right or authority to do big decisions for the world.
First, look at the failures of the Avatars: Yangchen failed the spirits multiple times and had bunch of broken promises that resulted in multiple dark spirits that resented the avatar, Kuruk did basically the same thing and even killed multiple spirits instead of solving the problem, Roku failed to see the inequality between benders and failed to stop his friend even tho he knew what his friend objective was, Kyoshi neglected her home country and her own secret force ended up stealing Ba Sing se, list goes on and the list is big.
Humans grant the Avatar the right of doing basically anything, but in the reality the Avatar is just an normal person which most of the training consists on bending trainings, they are not diplomats by nature and many of them failed to be, both in human conflicts and human vs spirits conflicts.
If you think about it, there is no logic in the avatar making big decisions and having authority in the whole world, both the spiritual and the human one. He is an human fused with an big spirit, sure, but that only grants them an great strength, not Solomon's wisdom or anything like that, quite literally just an stronger bender than the rest of human world, power which can be surpassed by technology in an few years anyway.
The point of the Avatar really being just an normal human that should not have the right to do important decisions is clear when you look at spirits interactions with the avatar: Most of them simply don't care. Some of them show some minimal respect but 99% of the interactions are based of them treating the Avatar like any other human, because he is. Wan spread the word that the Avatar is something special and is the bridge between humans and spirits, but they aren't, the Avatar is an human that in 99% of their lives they are heavily focused on being on the HUMANS side. The Avatar is an celebrity only in the human world.
There is no logic in the Avatar being able to do drastically decisions (like opening the gates, making promises to spirits that they can not fulfill, etc etc) and they should be punished if they do so. The Avatar should be one more strength of general humanity to deal with specific scenarios, not an figure of authority that can put its nose anywhere he wants to because he was born with that right.