Having just jumped from the 6S to the SE, in the end it feels like the 6/6S just aren’t as well considered as the 5 design was. Even at the same size the SE would be more pleasant to use. It feels as if so much work went into making the first large iPhones that they had less time to focus on actually making me them great day-to-day iPhones. Button placement, slipper edges, and other features make for some of the most usage-compromised aspects of iPhone design in the product’s history.
Yes, the market was demanding larger phones. The market isn’t always right, though, and it was a mistake(still is) to use producing larger phones as a reason to ignore deliberate design of a high-end "small" phone, where the experience existed and we would hopefully see much less sacrifice in practical design. It will still be a(design and quality of product-not commercial) mistake when the SE doesn’t get upgraded while the 7/7 Plus get released.