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.
I agree, the phones should still be phones and not tablets. If a customer want a tablet - buy a tablet. If they want a phone - buy a phone. 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.
Some consumers (myself included) don't want two devices that essentially do most of the same things but are just slightly different sized. I have the 6+ and like it a lot. I sold my iPad Mini Retina when I got the 6+ and for the most part haven't really missed it. If the iPad Mini Retina had phone capabilities, I might have considered making that my only mobile device, but that would have required carrying something to lug it around, so the 6+ is probably the best device to rule them all for me.