It's a mismatch with our intuition about how much effort things take.

If there's humans involved, "I took this data and made a really fancy interactive chart" means that you put a lot more work into it, and you can probably somewhat assume that this means some more effort was also put into the accuracy of the data.

But with the LLM it's not really very much more work to get the fancy chart. So the thing that was a signifier of effort is now misleading us into trusting data that got no extra effort.

(Humans have been exploiting this tendency to trust fancy graphics forever, of course.)

It is not limited to graphics, better packaged products, better dressed / good looking well spoken person and so on. Celebrity endorsements depend on this thesis.

There has always been a bias towards form over function.