Apple has made huge improvements to the iPhone since the 4S. LTE, 802.11ac, much better cameras, the lightning port, bigger screens, faster processors, six time

Apple has made huge improvements to the iPhone since the 4S. LTE, 802.11ac, much better cameras, the lightning port, bigger screens, faster processors, six times the RAM, four times the storage space, multitasking in iOS, 3D touch, multiple rear cameras, waterproofing, NFC for Apple Pay, wireless charging, and probably some other stuff I'm forgetting. There are of course going to be some people who aren't affected by those changes, but you're part of a very small minority and most users get a lot of utility out of their current iPhone compared to one that was released in 2011.