Developers should be upgrading on 2-3 year cycles max - the leap in performance of 2 generations noticeably impacts performance and unless you're doing some really trivial stuff - performance matters.
Check out Chrome build time benchmarks between 3/4xxx and 5xxx series (or any dev tool related benchmarks). 10-20% off your iteration cycle is noticeable - and that's a single generation jump.
Increasing iteration speed is a big productivity boosts, seeing professionals with 5+ year old devices is just ridiculous to me, you spend 8+ hours on that device - investing 2000$ for an upgrade every two years is not that much to ask.
Developers may have a reason to upgrade (many don't as ssh isn't going to get any faster-er with a fancy new CPU), but they constitute the part of people that read tech news. This is a minuscule part of general population.
Compiling Chrome is a nice benchmark but in reality dev cycles are quite smaller (or you might want to optimize your toolchain).
Finally, it's quite common for developers to forget the kind of hardware their users are running on. Then they produce software that only runs well on the next gen hardware. If you develop on a beast, then at least test whatever you are producing on a 3-4 year old machine to see how it will work for the clients.
Personally I'd like if developers stayed a couple of generations behind on their computers, so the rest of us aren't forced to upgrade regularly to keep software running at a decent speed.
Check out Chrome build time benchmarks between 3/4xxx and 5xxx series (or any dev tool related benchmarks). 10-20% off your iteration cycle is noticeable - and that's a single generation jump.
Increasing iteration speed is a big productivity boosts, seeing professionals with 5+ year old devices is just ridiculous to me, you spend 8+ hours on that device - investing 2000$ for an upgrade every two years is not that much to ask.