I honestly don't get why some people feel the need to upgrade EVERY time there is a new iPhone. Every other model is perfectly fine. It's not like the phone automatically becomes useless just because a new one is released. I've always gone for the S models, and it has worked perfectly fine for me. And frankly I've had zero issues with 3D Touch. Not sure if those of you who have simply lack any sort of finesse when it comes to how hard you press, but if it's a problem you can increase the pressure it takes for 3D Touch to activate.
I mainly agree with what you're saying about upgrading, however occasionally you have to get rid of a phone/tablet ASAP because it's not fit for purpose. Like the 6+ for example. That phone was lousy even before the 6S+ came out.