To offer a different perspective, I'll add that I greatly enjoy my recent model Macs. I use them professionally and in my personal life. I left PCVille long ago and am much happier. My first Mac, a white MacBook gave me 5 good years of service, plus 2 more sluggish years before being decommissioned in 2014. (R.I.P. whitebook 2007-2014)
Years ago, I enjoyed configuring my linux machine w/ various inexpensive yet effective upgrades. Sometimes this involved just swapping a card. Other times, rebuilds, kernel recompilation, etc. During my studies and early work years, I had plenty of free time, but very little money, so money was more valuable than time. Now that time my more constrained (demanding job, family, etc) the idea of spending my little free time on these tasks is extremely unappealing.
Put another way, upgrades are usually a means to and end: we upgrade the machine so we can do something that we couldn't do before. When I had a lot of time, this made sense. But now, I just want to get on with what I was trying to do.
From my personal machine I need portability, a good high resolution display, a command line interface with the usual tools (compilers, etc.) and reasonable CPU speed, disk space etc. I need it to handle media like music, movies, streaming nicely. And I need tools to handle media I create like photos in a reliable and simple way.
My MacBook Pro offers me these things. It looks nice, it feels nice to use, it works well and it will suffice for several years. There's value in the feeling that I can trust the machine to meet my needs. This is very subtly different from the feeling of knowing I can fix/upgrade/tinker my machine into a thing that meets my needs.
As an earlier post suggested, I chose to max out my retina MBP RAM and cpu. It hurt, sure. It hurt a lot. (Nearly as painful as keyboards!) But I felt it was the correct choice for me, so I sacrificed some other things, trimmed here and there, and ultimately bit the bullet. Haven't looked back, I am very happy with it.
I think the big objection I'm reading in this thread is cost. That is, if it cost zero to replace -- for example, in a bizarre world where trading the old computer in is worth 100% the cost of a new one -- it wouldn't be a big deal. In other words, the thread is not saying that as a matter of principle a machine Should be upgradeable.
And I get that; cost is extremely important! People have different needs. Different machine will meet their needs. For some a chromebook may suffice, while for others it is utterly useless.
Upgradeability is the main theme I read. It's worth asking the question, isn't it? We treat most of our devices as appliances; they aren't upgradeable. I can't (easily) upgrade my car, my refrigerator or TV. What makes a computer different?
Only that most were upgradeable in recent times, and some still are upgradeable. Maybe all these things should be upgradeable! That would be more sustainable wouldn't it? But the trend seems to be going the other way.
Many gawk at the price entry-level mech boards; we must be crazy here. Or, we have different priorities. So too with computers.
-R
