I don't mind the art style per se, it's the animation style I'm sick of. We have crazy good technology and shit is still animated like some super advanced flash animation. There's no more emotions and intentions behind the strokes of the brush like before. The line work is just consistent and bland.
Can't really blame the animation style, IMO. Most of these cartoons are produced under what are essentially sweatshop conditions in South Korea, and getting fine details and real artistry can very quickly pass the point of diminish returns. Animators and creators usually have a lot more time to develop the character models and the general look of the show. If the picture from the post thumbnail is from the show, then I'm saying that it looks incredibly uninspired and lazy.