It isn't a style.
It isn't a medium.
If it isn't from Japan, it isn't anime.
Anime doesn't mean it has a certain kind of plot or a certain artistic style, because there are shows from Japan that go against those grains since anime first came about. If you believe a cartoon to be quality, then just call it a quality cartoon. You don't have to needlessly rename Western cartoons "anime" just because you can't grasp the idea that a Western cartoon can do just as well as Japan can in the fields that you like in Japan's stuff. Just because you're playing a guitar riff from a famous rock song on a piano, doesn't mean you now have to call the piano a guitar.
You wanna make food comparisons? Here's a good one.
If you are from New York, go to Chicago, and order a pizza, you're most likely going to get a deep dish pizza. Why? Because that's what the most common and popular type of pizza is in Chicago. However, not ALL pizza made in Chicago is deep dish. And not all chefs or patrons who enjoy deep-dish pizza have any relation to the city of Chicago. You can eat deep dish style pizza without even knowing it's the popular style in Chicago. Just because it's the common style, doesn't mean that anyone doing something similar is deliberately imitating it and therefore has to classify itself as thus.
All of those things that you said were in Korra about characterization and whatnot? Those don't always exist in anime, but they also exist in plenty of other animated works from all across the world.
Any cartoon from Japan can be whatever it wants to be and still be a Japanese cartoon.
So why is it that when a non-Japanese cartoon has certain elements found fairly often in anime, all of a sudden it has to be a Japanese cartoon?