You can blame part of the problem on developers. Everything I've ever seen on a phone scales to your screen size perfectly. In Windows, many dev's do not consider different PPI (almost never considered in games). While most high end desktop apps scale, many custom and smaller named apps don't. This can make things very problematic for the user if they can barely read what is on the screen. In games, the UI is almost never scaled, making things difficult.
This is one of the big problems with every day uses, and in games you are hit with the added problem of needing more power to run games. Though this part could be a little over blown, as you can lower settings. But no matter how low the settings are set, I will never have 100+hz at 4k, which I pretty much require due to me need for smoothness (causes nausea if not).
Yah, but like I said, the resistance seems to go beyond scaling and GPU power.
I don't play FPS due to getting nauseous in every single FPS game I've tried. I wonder if high fps and G-sync will correct this for me. Hmm...