Why would you need 2/4K on a phone display? What are the benefits of that at the cost of battery and the fact that it would not provide any improvement other than tech specs?
Seriously old argument.
- I can shoot 4k video on my 6S+ - can't view it in 4k.
- I can access UHD or higher content on my 6S+ - can't view it in that level of resolution
- I can access/rent/view UHD+ movies and shows but can't view them as such on my ...
Your "comment" sounds like the old "the 3.5" is the perfect size" ... till it wasn't.
Battery impact is minimal at the worst. Android figured that one out just after the G3 launched.