@otacon
So by your logic, PPI means nothing. So anyone with a iPhone 4 or later has no PPI benefit over a 3gs, there is no need for 1080p when 480p will suffice.
Unless you mean to say that without native support, there is no difference with content for 4k over 1080p. But like it has been said, there is more of a need for these over content based use (games, videos, movies). The added virtual real estate will be welcomed.