Asus is right, the 5k is significantly more pixels than a 4k. It impacts every aspect of the experience; you need a better GPU, connectivity basically requires TB3, any additional in-line ports will be 'throttled', scaling tax, etc. The benes are sweet sweet retina quality hiDPI. That's basically it. If you like the smooth images then go for 5k.
It is a little like refresh rate to me. Lots of people chase super fast refresh rates and I can't tell the difference. I couldn't even tell you what my monitors rates are or if I've ever seen a fast refresh rate before. It's just not a thing for me. Some people are like that with pixels. They are fine with low DPI and don't see the difference between 2k and 5k (on the same sized screen of course).
Then there is the old Apple 'on average, 4k looks best on ~23/24 inch screens @1080 and 5k looks best on 27" screens @1440' deal. People dont like being hemmed into that box but Apple is basically right. So frankly, the market is isn't producing more 5k screens because there isn't demand. Sale rates of the LG and Dell monitors are low (Dell quit and LG is slowing production) and the general computer setup can't really deal with pushing 5k well (present interlocutors excluded, of course
). Heck, everyone wants/likes USB-C, which couldn't even handle 5k until 3.1, and even now it's not optimized for 5k like TB3 is. Basically, 5k is ahead of its time.
