I think this would have been pretty neat! I wouldn't mind if the series was aired, it's not like the franchise has anything to lose. But being the person I am, I'd probably preferred a Japanese Anime of the series over a Disney Animation. I feel like an anime could do better at attracting a more mature audience and storywise. Some of the concept art also seemed a bit weird to me, but I don't mind it much.
Most, if not all storyboards look weird expect when you have perfectionists drawing them. It wasn't concept art. It was just storyboarding to get the feel of the plot of the episode.
I personally have to disagree with that statement about anime. Most western audiences view anime and cartoons in general as a less-serious medium. Anime especially does not appeal to the majority of people in the west because they feel it tries too hard or it just looks weird.
The difference with the audience appeal of an anime versus a cartoon is that you'll find a western audience is more likely to sit down and watch a cartoon for a multitude of reasons (i.e. comedic relevance, quirky concept, watching with children, attractive designs). Since Kingdom Hearts has more popularity in the west, to me it makes more sense that if any animated show was to happen, deferring to Disney would be the best route.
A cartoon can tell a serious story and attract a mature audience (i.e. ATLA, Legend of Korra, Tron: Uprising, Star Wars, Young Justice, Green Lantern the Animated Series, Gargoyles, Batman the Animated Series/TNAB/Batman Beyond, Motorcity, Justice League, etc.) and still be full of quirky, fun moments and look really good while doing it.