And personally, I think that we passed the point of adequate specs for most purposes 8 years ago.

I have two MBPs. One is a 2008 that is beat to hell at this point but still functions pretty darn well with an SSD and maxed out RAM. It's good enough I've been able to do most day-to-day development with it and audio production up through this summer. If it were effectively invulnerable and weren't eventually going to stop receiving OS updates (or if security/compatibility weren't a concern), I could conceive of using it indefinitely for most work.

I also have a 2012 that is still adequate (though, weirdly, sometimes worse in terms of locking up, not sure if that's the later version of OS X or no SSD). I bought it not because I needed anything newer, but because I didn't want to be stuck searching for a replacement when the 2008 fails. And perhaps interestingly, I bought it used because Apple has decided to no longer offer a 15" model with a matte screen that's upgradable anymore.

Yup, Marco's take on this is a good one. (I bought a 2012 MBP in late 2015 for many of those reasons.)

One thing that is often overlooked is that the trackpad click is much better on the 2012 than on the Force Touch models. There is a really satisfying click, mostly because it has so much more room to travel. That was a big part of my decision to stick with the 2012 over any 2015 MBP or MacBook models. I feel about the 2012 MBP Trackpad the same way some folks feel about a Model M or Das Keyboard.

FWIW, it's also the only model available with a Kensington lock slot and an Ethernet port.

Great article, and one more point: The weight and terrible screen resolution are not show-stoppers for people like me who mostly use their Mac on a desk, with an external display. (Mine is actually a 2012 Air, but I barely move it and can absolutely relate to happy cMBP owners.)