If you asked any macbook pro owner if they were willing to spend money to double its RAM or HDD capacity I'm sure you wouldn't get many negative answers.
The price of upgradabilty is a heavier, thicker machine with probably less battery life (because they now squeeze the cells into every nook and cranny).
The ability to upgrade a machine is not a no-cost argument.
If given a blanket question of - ‘would you like to be able to upgrade your laptop?’ I’m sure the answer would be 100% Yes!
But, if you said ‘would you like to be able to upgrade your laptop but it will be half an inch thicker and a pound heavier?’ You’d get quite a different answer.
Based on what I've seen from non-technical friends and family, the standard approach to laptops is to buy a $300 netbook, fill it with crappy browser extensions and malware over a few years, complain that the computer is "too old and slow", throw it out and buy a new one.
It's really not, and it's quite obvious that the baseless assertion that no one wants to upgrade hardware is rather mind-numbingly absurd.
There are businesses dedicated to repair, upgrade and refurbish computers, including laptops. There are businesses dedicated to sell used hardware which offer clients a choice of processors and other components, including different makes and models. It's utterly absurd that we're supposed that this basic need simply vanishes in a specific form factor.