"Our intention with the last scene was to make it as clear as possible that yes, Korra and Asami have romantic feelings for each other. The moment where they enter the spirit portal symbolises [sic] their evolution from being friends to being a couple," DiMartino posted on his Tumblr account, while also acknowledging his surprise that they were able to broach certain adult subjects on "a children's TV network."
The other co-creator, Bryan Konietzko, was more direct in his Tumblr post in revealing his motivations. "We did it for all our queer friends, family, and colleagues. It is long overdue that our media (including children's media) stops treating non-heterosexual people as nonexistent, or as something merely to be mocked."
The idea that two characters in a children's cartoon were secretly lesbian may not sit well with most parents, although it should be noted that many of The Legend of Korra's fans were adults. While Korra's co-creators pat themselves on the back, and some adult fans celebrate the move, the truth is their "back-door" announcement seems more like a publicity stunt than a "brave" stand for LGBT rights.
If they truly wanted to make a "statement" about LGBT rights, the producers of the cartoon should have actually introduced it into the storyline before the series ended. By waiting until after the final episode to claim the female characters had feelings for each other, they avoided the likely backlash from the network, parents, and advertisers who would have objected to any depictions of a homosexual relationship (or any sexual relationship at all) in a children's cartoon. By waiting until after the show is off the air and posting such a revelation online in a blog post, they took no real chances. That isn't courage - it's a cop out.