I think the analogy is apt, but it's worth pointing out that most consoles are crippled against sideloading as an anti-piracy measure. They don't want you to be able to rip a game DVD, burn copies for your friends, and let them all play the game for free.
Apple prevents sideloading simply to have greater control over the platform.
Apple prevention side loading has the same effect and console manufacturers also gain "greater control" as a result.
What information do you have the confirms Apples doing it only for "greater control"? Would they also not want to prevent piracy in order to make their platform more attractive to developers?
What is the difference between a Nintendo DS and a iPod touch other than Apple has a wider range of apps other than games?
I don't know about that. Consoles tend to have strict certification requirements, and presumably the manufacturer gets a cut of game sales, both of which are reasons to prevent sideloading unrelated to piracy.
Apple prevents sideloading simply to have greater control over the platform.