These 27" 1440p displays are still only 110 PPI. Compared to tablet screens surpassing 300 PPI, reading on lcd monitors becomes so painful when you get spoiled on those tablet screens.
I'll be interested in 1440p when the displays hit 22 - 24" inch range and the PPI approaches 150. I'd really like to wait for 4k resolution displays to take off, and get shrunk down to 27". That would be much more reasonable pixel density. Using classic displays (or heavens forbid, an 800p laptop at 17") is just so jarring compared to my 250 PPI tablet.
Really? If ~300 ppi is enough at 10" away (retina iPhone) and ~200 ppi is enough at 18" away (retina MBP) then ~100 ppi should be enough at 30" away (large desktop monitor), right?
But what does "enough" mean? Regardless of eyeball distance, more resolution -- certeris paribus -- will mean the ability to display a superior image. I want 300ppi on a 30" screen.
"Enough" specifically means that if you increase it, or even double it, you won't be able to tell the difference. With 20/20 vision, your eye cannot resolve details finer than about one arc minute. (Note that 20/20 vision is, in practice, a limitation of the lens of your eye and not really the retina part.) So if you have better-than-average vision I guess you might need more pixels... or just sit a bit further back :) https://en.wikipedia.org/wiki/20/20_vision#Normal_vision
I'll consider it enough when I no longer get light headaches reading subpixel-rendered text on a desktop LCD at 18 - 24". My 1080p 22" display has ~100 PPI and that makes my head ache. That 27" 4k resolution display would have 160 PPI, which might be enough for me. But the 1440p 27" display only has 120 PPI and I still get headaches off that.
It is the same thing as FOV in FPS games. Some people get really bad headaches with narrow FOV on widescreens, some don't. If the 1440p 27" display is good enough for you, then just don't buy a more expensive 4k display at that resolution. Or get a 32" 4k display and get more space. I'm gonna get the 27" one because it feels easier on my eyes, probably at a price premium. I'm fine with that, I just want the pixel density.
You don't really need 4K at 27", even if your vision is very good you shouldn't sit that close to your monitor. 4K is awesome for large sizes, 32" and up, I would say.
4K at 27" would still be considerably lower pixel density (~160 ppi) than my old Motorola Atrix phone (275 ppi), which had lower density than my current HTC Rezound (342 ppi). I found the difference between the Rezound and the Atrix to be striking, so I think 4K at 27" would not be overkill by any means at half the density of the Rezound, even taking into account that the display will be a little farther from your eyes.
For larger displays - yes. For smaller - not really. After a certain density at a given viewing distance you stop seeing the difference, but doubling the density requires 4X more powerful hardware (and battery) to keep up.
I'll be interested in 1440p when the displays hit 22 - 24" inch range and the PPI approaches 150. I'd really like to wait for 4k resolution displays to take off, and get shrunk down to 27". That would be much more reasonable pixel density. Using classic displays (or heavens forbid, an 800p laptop at 17") is just so jarring compared to my 250 PPI tablet.