1) You can fiddle with the insides 2) You can fix it when it goes wrong
Despite what you may read on places like HN and Reddit, no-one in the real world gives two hoots about #1, and if you make a product that has good reliability then #2 becomes moot.
That's not true at all. I have plenty of non-technical people who chose to upgrade their laptops as time goes on, even if they don't do it manually themselves. Same goes for desktops.
Experienced bad memory on a MBP Retina (late 2013) recently, it was purchased in December 2013. You can't swap out the memory because it's soldered to the motherboard, so the entire motherboard has to be ordered from Apple and replaced.
This wouldn't be so bad if you could easily move the SSD to a new Mac, but that's not an option either.
It's harder to draw conclusions about how much absolute value is placed on it when it barely exists in a product category.
There's a reason why large enterprises still issue Lenovo/Dell/HP business class notebooks. A field technician with minimal training can fully rebuild one in an hour. That's not possible with anything from Apple.
I was reasonably glad I could swap more RAM and an SSD (twice) into my current machine.