If Katara had married Zuko she would've had a loving caring husband who would've treated her like a queen and would've treated their kids equally plus Katara would've been an ambassador in the Fire Nation and then Fire Lady, she would've had a huge political role and she would've used blood bending in so many good ways, she would've gotten a statue that she deserved so much, all this would've happened if she had married Zuko, but she didn't and I feel so so bad for her, it makes me so sad.
I don’t disagree with a single thing here, but I do want to address a misunderstanding that is likely to occur when non-shippers see this argument: the idea that Katara marrying Zuko would be a panacea for all the things that went wrong with her character in the post-A:TLA material.
Out of context, “Katara marrying Zuko would have made everything better” is only another way of Katara’s destiny hinging on who she is paired with romantically. So let’s talk for a moment about what we actually mean when we use that as a catch-all phrase for A:TLA’s improvement:
A return to the themes and symbolism that A:TLA espoused. As I explain here, a lot of the themes of A:TLA were subverted in order to make the canon pairings happen. If the creators didn’t force a romantic pairing between Aαng and Katara, her character would have been better served because motifs such as “choosing one’s own destiny” would have played out naturally through her development arc.
More creative control by A:TLA’s best writers. Bryke had no writing credits to their name prior to A:TLA, and a lot of the best writing work on the series was done by Aaron and Elizabeth Ehasz. These two had a special focus on Zuko, but they refused to succumb to the temptation of making Zuko the guy who just “gets” everything in the end because he’s the hero. Unlike Bryke’s favorite character, which leads nicely into …
The series would not have played favorites with Aαng. This is a major part of what annoys people with the A:TLA finale, and leads to further problems in Legend of Korra. Aαng is not allowed to go through the same soul-wrenching struggles as the rest of the characters. It’s not that he doesn’t suffer, or he doesn’t lose people, or that he isn’t conflicted. It’s that his core beliefs are never challenged in a way that makes them develop. In the show, it is reality that always bends to Aαng’s beliefs, instead of Aαng having to adapt his beliefs to reality. If you go back through A:TLA and compile a montage of all the times other people learn that Aαng was right and they were wrong, you would a) understand what I mean, and b) understand how damaging that is for a protagonist, the person you want in your show to change the most.
Katara’s agency as a character. It’s safe to say that Aαng, in the context of romance, is detrimental to Katara’s agency as a character. We see this when side characters repeatedly encourage Aαng to pursue Katara “because you’re the Avatar”, even though they have never met Katara and have no idea what her opinion is on this romance thing, if she even has one. We see this again when Aαng kisses Katara without her consent and never apologizes for it or brings it up again. And we see it in the comics, where Katara’s ideals are Aαng’s ideals, they never have any conflicts, her feeling abandoned by him is portrayed as wrong, but her approval of Aαng’s potential murder of Zuko is right, her leaving it up to Aαng to decide whether the Four Nations should be forcibly separated is portrayed as right, and her old Water Tribe friends accuse her of having forgotten her homeland because she spends all her time with her boyfriend.
Avoidance of black and white morality. One of A:TLA’s strengths as a show is that it portrays a complex world. There are lessons to be learned and characters with strong moral convictions, but there is rarely a sense of one set of principles being lauded over all the others. In fact, a sense of moral superiority without listening to other points of view, such as the Fire Nation has, proves to be highly destructive to the world at large.
But when it comes to Kαtααng, this complexity falls by the wayside. Zuko the morally ambiguous deuteragonist is suddenly the “bad boy” who “doesn’t really care about [Katara]”, despite the fact that he risked his life for her in the finale. Arguably the most complex episode of the series, “The Southern Raiders”, is seen by Bryke (who did not write it) in purely good-vs-evil terms, with Aαng being the “angel” and Zuko being the “devil” on Katara’s shoulders, respectively. Oversimplification of morality is something that plagues Legend of Korra to a major extent, with the embodiment of that being “goodness” and “badness” personified in Vaatu and Raava during Book 2. (Notice, too, that Katara in LOK had bloodbending outlawed, instead of her embarking on a similar journey to Zuko in “The Firebending Masters”, where even seemingly destructive bending could be used to create life.) Black and white morality in LOK has its beginnings in the tail end of A:TLA, with the boy who could not be allowed to kill under any circumstances, and who is, quite literally, a Nice Guy.
Sokka: The number one mistake nice guys like you make: being too nice.
So, to translate: “all this would’ve happened if she had married Zuko” = “there is a natural narrative thread that would have culminated in Katara having a relationship with Zuko if it weren’t for the executive producers derailing it, and her character, for the sake of their own pet character who was in many ways a self-insert for them both.”