Also waste of power compared to screen density and power. I'm sure you're one of those people wanting a 1080p screen. Huge waste of ressources for what it is. When I compare my 1080p SGS4 screen to my 544p Vita screen, difference is noticeable but definitely not worthy.
Subpixels.
![samsung-galaxy-s4.jpg](http://cdn.gsmarena.com/vv/reviewsimg/samsung-galaxy-s-iv/preview/samsung-galaxy-s4.jpg)
![xperia_z-vs-galaxy_s4-pixel-density.jpg](http://content.mobile88.com/news/wp-content/uploads/2013/07/xperia_z-vs-galaxy_s4-pixel-density.jpg)
Various AMOLED diodes wear out faster than others which is why Samsung often uses a strange layout while the standard for LCDs is a simple RGB color strip. The Galaxy S3 is the biggest offender with its Pentile layout. You literally see dots on the screen FFS...
Going back to the Vita I checked the AMOLED in my microscope (old toy with just 300X using my hand as focus) and saw that it had a color stripe that looked like the Galaxy S2 one. The pixels aren't quite as big as LCD ones which is noticeable on a white screen, but it looks a million times better than the Galaxy S3 which has a higher pixel density.
![galaxy-s-family-microscope.jpg](http://www.blogcdn.com/www.engadget.com/media/2012/05/galaxy-s-family-microscope.jpg)
1080p is overkill, especially for a gaming focused device when mobile GPUs have such limited bandwidth (the Vita struggles to render half of that). That doesn't mean "make another crap screen" though Nintendo -_-
Edit: *DOWN ARROW* Intel has tablet SoCs ready for 1440p. Just means they won't completely fall flat showing 2D graphics and doesn't make them powerhouses though...