Sucker logic.
Samsung and other OEMs keep recreating new hardware because their users can't get the latest release of the OS. They'd rather force them into buying brand new hardware. Android is being released at such a pace the OEMs and carriers can't keep up, so they ditch their current customers and just move on to new devices. And maybe, eventually put out an update... MAYBE.
I know a ton of people still using the 3GS as their phone. Why? Because over the passed 3.5 years, Apple has offered 3 OS upgrades; 3.0 - > 4.0 -> 5.0-> 6.0. Most people don't care about new hardware, they just want their phone to continue working.
People who do upgrade to new hardware may not be interested in how it looks but other aspects: better screen, faster performance, etc.
When I upgrade ANY product or device, it's not because of how it looks, but rather what it's capable of doing better than the current device I have.