Re: Why upgrade?
Agreed. All the upgrades these days are just incidental improvements to OS and styling really. The hardware boosts are like making your car go 201MPH instead of 195MPH--unless you have eagle eyes or are into hardcore gaming on a tiny screen, most people don't notice them.
I'm still using my old Galaxy S5 and will probably keep doing so until something goes wrong with it or I get sick of its comparative slowness. The camera's still good, the SD card slot and replaceable battery keep it relevant. (and the IR emitter comes in handy too)