I hate to be "that guy" but .. you're debating something which isn't debatable. If you want user serviceable parts, Apple isn't really for you. Nothing anyone says on here is going to push them in another direction. Their customers are buying their products because the majority of end users do not upgrade their PCs or even know how to, much less fix anything. That user base is so small Apple, as well as most other companies don't need to make them happy.
A few others above have said it, but... Apple have in the past been an "enabling" company. They've always gone the extra mile to make certain things easy to do - that includes upgrading your machines. Right from the get go they've included expansion ports, and guides on how to replace certain "user accessible" parts.
About 6 years ago they went all-out on their notebooks and actually started designing them specifically with this in mind. RAM slots gained easy to access triggers or panels, and the "number of disassembly steps required" to access HDD and optical drives reduced dramatically.
Then, as someone else said, with iOS and the MacBook Air, this suddenly stopped happening. It was a complete shift in their approach.
And to all you people claiming it's impossible to make a machine as thin and powerful as the rMBP with upgradable components I call BS. Dell's just done it with the New XPS 15. And I'm pretty sure that M.2 connectors would fit exactly where the SSD is on both rMBPs. I'm also pretty sure that they could fit a daughterboard where the RAM is currently soldered, even if they had to use one of the smaller DIMM standards, and even if you had to remove the logic board to plug in a DIMM.