Doesn't it depend on how close the device is to your eyes? Also just because the individual pixels aren't visible doesn't mean there's a noticeable difference in picture or animation quality. Just because Apple claims that "retina displays" use the smallest pixel size noticeable doesn't mean it's true.

Edit: Google search on the topic: http://mostly-tech.com/2013/11/08/debunking-the-retina-displ...