I think current Hollywood is a prime example of doing objectively bad art especially live action movies. They ignore the source material to make it fit their political agenda, which has always been a thing, but it becomes problematic when it breaks the characters and rules of the world. The stories become so inconsistent that you just cannot get immersed. Knowing more about the writer than the characters is really bad writing.

I also consider the all knowing character very popular in webtoons to be just a form of cheating. I've seen it done well, e.g. knowledge as a double-edged sword, but mostly poorly to the point it could have been removed and the story would have been the same. In general adding superflous elements because it is trendy is really shallow writing.

something that dilutes itself and tries to appeal to everyone and yet very few people actually like it.

of course "bad art" is a ridiculopus concept in some sense, but I think here the issue is a total lack of "art", an entirely cynical attempt to hit the exact average with no ideas behind it