I'm speaking from experience. I'd really like to be able to add more RAM to my MacBook Air. 4GB isn't working out as well as I had hoped. I knew about the RAM being soldered to the MB when I bought it, but I figured I'd be financially able to upgrade by the time the amount of RAM it had became a problem. Unfortunately, I'm not able to do that. I cannot afford to upgrade.

Also, I do upgrade every N devices. I'm not someone that buys the new model everytime they release one. I guess I should have phrased it "because not everyone can afford to upgrade to a new device".