No it's not that they don't actually understand. The issue is that Apple has not yet endorsed it in THIS product so "nobody needs it," "it's stupid", "useless", "until every possible video in the iTunes store is available in 4K", "the chart" and on and on- the exact same collective mentality when Apple still clung to 720p MAX in

TV2 while pretty much everyone else had already embraced 1080p.
Once Apple rolls out the

TV5 "now with 4K", all this sentiment immediately evaporates... just as it did in the "720p is good enough" days. "We" will make up 100 reasons why 4K makes no sense now- most are identical to why 1080p made no sense then... but once Apple goes there, "we" won't call Apple out for stupidly embracing "the gimmick" with differences "I can't see (so you can't either)", etc.
Of course, you don't see those who pooh, pooh 4K so readily in

TV threads over in iPhone threads applying the very same arguments against a product where Apple has already embraced 4K. Apparently, there it is perfectly fine, even "shut up and take my money"? Same with iMac's editing 4K, iPad Pro editing 4K, FCPX 4K editing and output and on and on. It's just "dumb"
here- in this
ONE Apple product- but only until Apple adopts it... and then Apple won't be dumb for doing so. Only us consumers who now express a personal wish that Apple had gone ahead and embraced it in this "4" are dumb because, you know, Apple is always right in all things. Don't actually "think different." Comply. Resistance is futile.