When you've been using iOS for years it all gets a bit samey but when Apple also make your phone look the same for three handsets on the bounce it all becomes very dull. The 6 Series wasn't an especially nice design to start with, so sticking with it for the iPhone 7 was a step too far for some of us. I'm using the Xperia XZ until the iPhone 8 comes out...and it better be good because I'm loving my Sony.
People buy the same model car that is simply of a newer year but is very similar to what it has been for a few years with just a few visible changes here and there and just more under the hood and other internals and gadgets. And it's quite a bit like that with clothing too, especially on the higher end where people will not only buy slightly updated versions of what they like but even exact same ones in multiples or again and again as they might need or want them. This kind of thing has been much more prevalent for much longer period of time when it comes to many things in our lives that have been around for much longer than smartphones or even cell phones.
The iPhone 6 and especially the 6+ were short on RAM and crippled from the start. Multitasking enjoyed previously on the iPhone 5 was dead and the 6+ regularly froze up it was so RAM-starved. The 6S corrected this so nobody is saying that the iPhone 7 isn't a dramatic performance upgrade from the iPhone 6. It's not even so much that the design is stale, it's the fact the design is behind the times. The 4.7" phone is too small for a modern smartphone and the 5.5" is so impossibly unpocketable due to the huge bezels.
