Many other manufacturers make phones with virtually not existent bezels. the LG G3 is an excellent example. It's shorter than the 6 and only a hair wider yet has a 5.5" screen.
The technology is capable. I'm pretty sure the bezels were an Apple design choice to maintain "iPhone proportions." It's a mistake.
Yes, that's why I love my G3. Those bezels make the difference:
http://www.phonearena.com/phones/size/LG-G3,Apple-iPhone-6-Plus/phones/8347,8908