Eh, I think you're allowed to watch cartoons even if you aren't in the target demo. I've watched most of the cartoons mentioned in the article as well as a bunch of anime, all of which I'm a fair bit older than the intended audience. I also don't think it's a problem that all of the cartoons have a somewhat similar style, given how many people there are who worked on several of the same shows who presumably influenced each other. And I dunno why the fact that the new Thundercats look like the characters from Steven Universe is any worse or less original than the fact that they used to look like generic musclebound 80's cartoons.
Basically this is just stupid turbo-nerds trying to find a reason why everything from when they were a kid was so much better, even though it quite frequently wasn't.