PCMCIA does a similar thing for laptops - you'd just need to expand the scope quite considerably.
Erm. A large number of laptops require you to remove the frakking KEYBOARD before you can even get at the slot the memory is in.
Sure, we could make an easily upgradeable PC. We as in the PC industry as a whole. It'd also be completely incompatible with all the parts that currently exist. So who's going to be the first to take a gamble? Build an entirely new manufacturing line, do millions of dollars worth of R&D, millions more of testing, get the word out on the street with a massive ad campaign, etc.
It's really easy to sit here and bleat "Hardware manufacturers should just do blablablabla".
But if you take five seconds, ask yourself why THEY would do it?
Btw, things like that have been tried before. Back in the 80s, a bunch of manufacturers combined to form a standardized hardware base. All computers were identical, and the idea was that they could be easily upgraded etc.
MSX it was called. It was a great idea, until they realized that nobody was buying them. So which manufacturer is now going to take a hundred million dollar gamble, for what in the end will amount to zero extra profit?
What's in it for the hardware manufacturer? The answer is : Nada.
Creston