Kataang: Yes, it's canon. People like to squee about it being canon. That doesn't make them "boring sheeples with no imagination" or "assholes". They like it cause they think it's cute. And no, Bryke wasn't "masturbating" over it, nor did it happen just because he's the hero, she's the heroine and the writers called it "destined". Aang and Katara were friends first and lovers second, they grew together over the course of the story and were genuinely in love, even if she was confused during "The Ember Island Players".
Maiko: Fine, so Mai isn't the kind of gushy emotional melodramatic motherly maiden people wanted for Zuko. Maybe the relationship needed a little more airtime and development in canon. That doesn't make it "strangled by the red string" or "gross", nor is Mai a nasty bitch who likes fruit tarts more than she likes Zuko or would kill Katara's unborn steambaby out of jealousy. (And no, Sokka does not hate Maiko either.)
Zutara: Yes, I'm defending Zutara. I personally don't like the pairing, and find 90% of its fans obnoxious. But I don't agree with people pegging ALL Zutarians as butthurt whiners who just wanted their ship to become canon. And even if there was no way it was gonna be canon, even if Bryke WERE trolling the fanbase a bit, that doesn't make shipping it wrong or immoral.
Sukka: This pairing could've used LOTS more canon screentime and development. But just because Sokka is close with Toph and still wibbles over Yue doesn't mean he doesn't love Suki as much as he loved Yue/"should" love Toph.