The point was that the 6+ sales exceeded the forecast by a significant margin. This same size debate goes on inside Apple, and Steve Jobs even highlighted the intense scruitiny they put on size when designing the iPhone, and the "Giant" (in Apple's words) Samsung Galaxy and Note phones were outselling them. And Apple released the 5s / 5c which tested some aspects of the equation, and they release the 6 / 6+ which tested the size question. Given those two market tests one might presume that Apple learned 'plastic was not a good material for an expensive phone' (under performed the forecast) and 'larger phones have significant appeal' (over performed the forecast). And as I stated outside Apple's testing this hypothesis there are a bunch of different Android phones in different sizes and they too inform on market acceptance or rejection of various design choices. The age old model of 'buy what you like, they will make more of them' is more true today than it ever has been, manufacturers are so intensely watching and tracking the buying habits of their customers that feedback is immediately implemented in products in the next round (you'll notice neither the 6 or 6+ are 'colorful' :-)