Why all the hate for 720p screens?

First of all, let's try and please not let this turn into an Apple vs Android thread. That's not my intention at all, I'm really just curious about something and am hoping someone can shed some light for me. It seems like 1080p is considered the standard for "high end" Android phones now. If a phone has a 720p display it seems like it's automatically considered a "mid range" phone. The iPhone 5 however has a lower resolution than even 720p and yet it still seems to be considered one of the best phone displays on the market. Is that simply because the quality of the display itself is that much better, or because it's only a 4" screen so has a higher pixel density, or something else entirely?

Also, on a somewhat related note, is the difference between 720p and 1080p really noticeable on a 4.7" or 5" screen? I remember when 1080p TVs first came on the market people were saying you had to have at least a 50" display for the difference in resolution to be significant. Obviously we are a lot closer to our phones than we are to our TVs (at least I would hope so for your eyes sake), but I'm still wondering how big of a difference there really is on such a small screen.