Since you are so sure about how Mac Mini's are used, is it 2k on 24" or 27" that these customers use?
My impressions based on limited anecdotal data I've is that most people with mac mini are using it as their secondary device (everyone has a Macbooks). Everyone is using 27" 4k monitors. 4k monitors are not that far from 2k monitors, and I think most people who are preferring to buy 2k are gamers that want higher refresh rate that their GPU can support at 2k. But gamers are not using Mac's anyway.
Viewing distance matters. ppi isn’t the target metric, it’s pixels-per-degree-of-vision that determines if a display setup is “retina”. 60 ppd is equal to 20/20 vision in a human.
My 34” monitor is only 4K but is “retina” at the viewing distance in my home office according to this calculator:
https://qasimk.io/screen-ppd/
My impressions based on limited anecdotal data I've is that most people with mac mini are using it as their secondary device (everyone has a Macbooks). Everyone is using 27" 4k monitors. 4k monitors are not that far from 2k monitors, and I think most people who are preferring to buy 2k are gamers that want higher refresh rate that their GPU can support at 2k. But gamers are not using Mac's anyway.