Caleb Gross has the clearest framing I've read for why so much AI output feels hollow:
Creation is the distillation of intent into form. Intent is usually inseparably embedded into the form of the artifact. A human iteratively (sometimes painstakingly) shapes and reshapes their creation until it sufficiently matches what's in their mind's eye. The odd thing about generative AI is that it can produce substantial form with minimally applied intent.
By that definition, humans are very capable of generating slop, too; generative AI has simply lowered the entry barrier for creating intentless form.
Slop isn't an AI problem; it's form with almost no intent behind it, and AI made that cheap.
https://noperator.dev/posts/you-can-just-say-it/