To be honest, I'm fine with the 27" the way it is. More res = more money, more resources needed to drive the screen and more heat. I see the advantage on a screen that is held close to your face, but not so much (yet) on the 27" one. I'm sure it would look nice, but at what cost overall.
Totally agree, it's just like the delirium that is going on with TVs with the 4k resolution....unless you sit a few inches from the screen the human eye simply can't perceive the difference, net it's totally useless.
Unless, that is, there is some app that requires you to examine a mega screen from a few inches -i.e. medical X-Rays, etc., albeit i don't know why you wouldn't simply pinch&zoom-