E: I'd like to clarify I'm including stuff like no USB ports in walled garden.
I think people have accepted the walled garden model and they like it.
In a perverse way, their success is partly because of the PC era itself. The lowered expectations people have of computational devices from windows makes. Having something that "Just works" such a blessing, for such a ridiculous portion of all consumers, that their "walled garden" translates into "sanctuary" for most human beings.
IF in the future mature market, other tablets have also reached a stage where "it just works", then its an even playing field.
At that point,the walled garden will be just another field to walk between.
Edited for clarity