I love the feel of the 15" rMBP (mine is sometime in 2013), though I don't think it's any different than earlier non-retinas, at least in key travel and size. The new low profile MacBook keyboards are almost unbearable to type on compared the nice feel of the current and Apple external keyboards.

The current Magic Keyboard has excellent tactile feedback. Key travel is short, but not too short, and feedback is clear and crisp. The tiny arrow keys bother me a bit, because I use arrow keys a lot. Overall, I find it to be much better than the 2015 MBP with it's “butterfly” mechanism.

Oh, external keyboards are a very different thing as you can go over board with customizing them (myself am using an Ergo Dox).

But the built-in keyboard you can't switch. And there's situations where you can't be bothered with bringing your external KB around. So it's still important how the built in feels.

The non-retina MBP keys have less sideways "wiggle", require just a touch more initial pressure to actuate, and have a slightly greater travel. Compared to my rMBP, they have a delightful tactile "crispness" and give the device a feeling of precision.

If I were a hardware guy I'd put that keyboard in its own case and use it forever :)

That sounds consistent with my experience with the older Apple Wireless Keyboard (second or third gen). I always wished they'd make one with black key caps and the backlight.

I have the same model, totally agree! I think 2013 15" rMBP was the pinnacle of apple laptop design.