LLMs seem to revel in throwing layer after layer of decorative paint in the hope that people will fail to notice that they're not actually painting anything.

Length or duration is considered, erroneously IMO, to be a measure of completeness or thoroughness. Pithiness is valuable, and is a skill that can be honed. I guess padding out your writing using an LLM is equivalent to adjusting the font size and margins on a "three page essay" to meet the minimum requirements.