Agree 99% on this. My 2012 rMBP (i7 quad core, 16GB RAM, 512GB SSD, and NVidia discrete graphics) still runs like a champ with VMWare running in the background supporting a docker swarm nonetheless). The only upgradable part in this system was the SSD and I upgraded that from the original 256 to the one that's in there now. The keyboard is actually starting to wear out with the 'S' having all but disappeared from the 'S' key.
All I was hoping for was this exact form factor with upgraded internals (faster CPU, faster GPU, 32GB), swapping the two existing Thunderbolt 2 ports for Thunderbolt 3/USB-C ports. But no, apparently we all wanted lighter and thinner, no function keys and only poorly supported (so far) USB-C ports. Who knew?
By the way... TB is not useless. I use it everyday. I plug my rMBP into power and then plug a TB cable in from my computer to my LG Thunderbolt display with builtin USB-3 hub and TB passthrough.
Switching to the 9560 (from a MBP) wouldn't be as easy as one would hope. WSL is very very slow and awkward to use compared to the macOS terminal. Part of the performance problems are related to forking: on *nix forking is a lightweight operation and used a lot, especially in all of those convenient BASH tools that we use (like RVM) but on Windows it's a very expensive process--I'm rewriting GVM2 to speed it up for Go development on WSL. Then there's the whole deal of having to double up on your installs (e.g. installing ruby dependencies on both Windows and within WSL for code completion support, etc., from within VSCode) and not editing WSL files within Windows or risk corruption.
Then there's that single 2-lane Thunderbolt/USB-C port and the 9560's 130W power requirements...sadness. While an HP Zbook Studio G4 (also quad core i7, all the way up to Xeon) includes two 4-lane TB3 ports, it has older Quadro 1200m graphics and comes with a 150W power adapter (!): way way out of the max 100W USB-C spec. And yet the new rMBP still only draws something like 87W. In short, you can't charge any of these machines over USB-C unless they're idling.
It's like being stuck between a rock and hard place right now: Apple caters only to the mass consumer while everyone else is spread so thinly across all markets that they can't seem to focus and make a truly awesome MBP replacement for power users (engineers, creatives, scientists, gamers, etc). And I look at this 5-year old rMBP with its totally smooth underside, still incredible display, properly placed speakers and webcam, and wonder why Windows notebooks still can't compete with this Jobs-era design.