Earlier quoted context omitted.
It's a 15" screen! For 4K to even begin to make sense, you need a 40" diagonal, and with your face about a foot away from it. (For a more detailed explanation, ask a local fifth grader.)
40" diagonal seems a bit extreme. I think my 27" 4k display is perfect. My dad has slightly worse eyes and prefers his 32" 4k display, which I find noticably grainier but perfectly serviceable.
Putting a trio of portrait 24" 1080ps gives you 42" of almost 4k (3240x1920 as opposed to 3240x2160).
I don't see whats extreme about this at all, its a better use of area than my trio of 24" 1080ps (in landscape) that I use now.