Comment sections like this are why HN is called an echo chamber.
A clearer chart is at [1], and the Carlton Bale's original article even has a handy calculator that lets you verify this [2].
1: http://s3.carltonbale.com/resolution_chart.html 2: http://carltonbale.com/does-4k-resolution-matter/
I'm not at 2 feet with a smaller dual display, and I'd imagine I'd sit further away with gigantic 30+ monitor(s). I know I do when I use a 27. Others at $work mostly sit at least as far away.
In this area of improved vision, what does it gain you? Did all the old hackers not amount to what they could have been because they perceived some less pixels than there could have been?
I don't think a serious argument can be made on this this front until standards reach at least 16k.
Incidentally, given that displays seem to be continually trending larger, I expect that we'll eventually have an entire wall in our homes that's a display. 4k is just another step toward that.
but hey if you sit < 2' from a 28" and have no problems with that, then go out and grab you one