I think the screen is a function of how large the phone is and not vice versa. The phone has grown because of everything they've packed in there. The screen is the size it is because that's the best fit for the size they ended up with.
Pretty common misnomer - that bezel isn't there for show - it's concealing the tech that was too much to hide behind the panel (or wouldn't work well behind a panel like a modem).
It's one of the reasons I get frustrated with people who go on and on about the M8 "extra bezel" it's as if an entire legion of stupids actually believes that it's there jsut for show - and it's hollow behind it and all you have to do is elliminate empty space...which is inaccurate!