Not that you're wrong but researchers are also deeply imperfect. They're rushed, they're given no time to actually improve their work, and the emphasis is entirely on 'good-enough' publications. The number of times I've been involved in a paper where the mentality wasn't "get it out the door, now" is.... zero times.

Plots often fail to clarify for the precise reason that clarification takes time and effort and those things are lacking in academia in spades. Are people intentionally hiding ugly details, definitely on occasion? But I don't think it's the primary source of such bad figures.