Deus Gladiorum said:
Honestly, who cares? In my experience, anything with a ppi between 100 - 150 is what you need to view something at the sharpest possible image from around a foot away. A ppi higher than that just results in wasted image quality. A ppi lower than that creates aliasing. So why the hell do you need anything that's over 500 ppi? You're not going to notice any difference from a foot away compared to the same size screen with a lower resolution.
Speak in the first person to be more accurate
. It is appropriate for you to say "I" can't see the difference, but you have know idea what other people can observe, or what they are sensitive to. General analysis of human sight always comes with caveats, as well; blanket statements about what the "human eye" can see are usually wrong.
I don't have a cell phone (yet) and don't use any device with such a small screen. However, I've read a Tomshardware editor say he couldn't see the pixels of a 30" 2560x1600 display. That just floored me, because I can see the pixels on a 27" 2560x1440 display, which has a better pixel density. Now, we aren't talking 300 PPI as opposed to 500 PPI here, but we are talking over 108 PPI for the 2560x1440 27", and I can certainly see the pixels on this screen (and my vision is far from perfect). Whether I could see them with a PPI of 150, I don't really know, but I bet I would still want a higher density than that. 500 PPI? I'll just have to see it to judge it properly.
Useful or not, it IS progress in technology, and that's good. One thing I can think of - LG might actually be able to create a screen of this size and resolution that has dead or stuck pixels at 500 PPI that simply can't be noticed, that turns out to be cheaper to make than a screen with far less resolution needing every pixel to display perfectly. But it harms no one, and the market will certainly determine its value - not many people will actually buy a phone if the screen causes the battery life to plummet unacceptably.
Even if it is turns out to be just an exercise in manufacturing technology, implying that no one does or should care is simply wrong. We aren't all carbon copies of you, and I, for one, care.