Phones will get to where computers are now. If you think back 20 years, 4 year old computers could not run just released software. It took time for two things t

Phones will get to where computers are now. If you think back 20 years, 4 year old computers could not run just released software. It took time for two things to happen: 1) Increase in available computing resources; 2) Commoditization of the platform. It can be argued that we are just reaching condition (1), but we are still a bit far from (2). The peculiarities between hardware platforms make it necessary to actually test on each hardware platform. As the installed base of a phone dwindles, after a point it makes little sense to provide updates. We'll get there, but it'll take a few more years. In the meantime, Nexus are great choices, because the developer community can actually fill in for the necessary testing and tweaking. I had an HTC Desire before my Nexus 5, and it was incredible how much its life was extended by a vibrant community (mine lasted over four years and was clearly outdated spec-wise when I bough the N5).