I don't want to make this sound like I am disagreeing with you in principle, because I do value software freedom, but when I get a tablet or a smartphone, I expect it to just work out-of-the-box. These things excel at being consumption machines, not production machines.
The target audience isn't necessarily a tech savvy one. The more the user is allowed to do, the higher the potential for mishaps. When you promise a customer a fancy piece of shiny hardware and advertise it like a high-tech toaster - "press here, then magic happens" they aren't expecting a full blown PC with all the associated quirks, tweaks, gradual cluttering/slowing down/ buggyness, etc. They are expecting a magic little plastic box that does all the things that were printed on the outside of the big cardboard box it arrived in.
Every additional copy of whatever-it-is is more junk, more clutter, more slowdowns, and the device will not run as advertised for long, by locking things down, it lets the manufacturer ensure the device works the way they want it to until they make it obsolete.
If I want a device that works the way I want it to, I stay away from Apple, tablets and smart phones, and get a real computer.