Earlier quoted context omitted.
An iPad is not a phone. An iPod Touch is not a phone. Even on phones, many, maybe most, aspects of the lockdown have nothing to do with carriers' interests. Apple has decided it likes being like a carrier; its relation to users has changed from computer company to jealous boyfriend. (I'm not getting involved beyond your first paragraph.)
There is a spectrum of openness when it comes to computing devices. At one end you have computers that are very open, with all of the problems that come with that, and at the other extreme you have fixed-function devices such as printers. In between, you have things like game consoles, smartphones, and other mobile devices. iDevices are more closed than computers, sure, but they are much more open than say a Nintendo…
Where I'd expect them to be: no correlation a priori between whether a computer has a multitouch interface and whether its own owner can choose what software to run.