I don't know if there's data to support this but from what I can tell Linux users are just poorer on average. So it's not like they think low res screens are "sufficient", most of them just don't think it's justified to pay twice as much for a better screen and the market just reflects this. Or maybe I'm just projecting my own views on the issue.

Doesn't matter though because things are changing, native Linux device makers like S76 and Tuxedo provide have started providing 4k screens on their models.