I genuinely cannot see the pixels on my Samsung S5 without a magnifying glass. They were noticeable on my Zenfone Max if I brought it close to my face, but it wasn’t visible at longer ranges for me. Your eyes are obviously much better than mine. As for putting higher and higher resolution screens on, of course they won’t do it to deliberately increase the battery drain, and of course, people tend to pick the thing with the nicer-looking number after it (sacrificing things like battery life or being able to repair it in favour of having a thinner device).
Desktop monitors have the advantage of being extremely large compared to a phone screen, so the extra pixels would be more readily useful. Regardless of that, however, you notice pixellation at 1280x720 on a 5" screen, so it is indeed a potential issue.
I personally wouldn’t complain about having a 1920x1080 screen, but my absolute #1 priority is a phone that will have a very hard time betraying me (read: all communication components are separate from one another, may only talk to each other with the explicit consent of the software running on the main CPU, and have absolutely zero influence on anything else) and as such I don’t want to strangle it in the crib with feature creep. I’ve already seen the GTA04A5 die, I’d rather not see another similar project fail for whatever reason (whether it’s delays in sourcing more panels, or difficulties in getting an as-yet untested CPU running, or anything else).
And yes, backlight level does have a much larger effect on power drain than the processing power to render more pixels, but that tiny little overhead is still there.
The contents of that link do look promising so yes, Exynos chips might be a possibility. I admittedly do not know that much about the state of free drivers for mobile graphics acceleration other than PowerVR is complete crap and that Adreno has only the beginnings of a functional driver. I don’t know enough about the other things (how easy is it to get them, what other components do they contain which need drivers, what possible security issues exist from the chip’s design) to say any more. Again, I just want it to work, and more importantly, I want it to actually exist.