I'm not quite sure. I went to an iPhone 6 (6, not 6+) and want my iPhone 5 back. Companies responded to consumer demand but I think this is largely a case of consumers not having a clue what they actually want.
On the other hand what Apple made with the 6/6+ is a decent solution even though personally I believe the iPhone 6 to be slightly too big as well. Had to purchase a silicon case just to get a firm grip when holding it.