So (part of) your argument is that tablets in general have less built-in utility, and iOS tablets have access to a huge range of apps and content to make them useful than other tablets don't have access to. While that's true right now, I don't see why this will be the case in the next couple of years.

First off, apps: I would expect an increasing number of apps to be released multi-platform, for iOS and and Android and possibly for Windows P.O.S., because hey, why not release it multi-platform? The web is an important special case of multi-platform development and Google is keen on establishing web apps as just apps, too.

And content: While Apple owns a huge amount of the market, they don't own the actual content and I don't see why the content owners would restrict themselves to just one distributor. They'd reach a wider audience and they might even get a better deal if there's competition on the market.

The situation with the iPad might be similar to the iPod, but I don't think it's because of the content ecosystem. As you say, there are many other ways of obtaining MP3s, including many legal ones. I'm sure Google Music or Play or whatever they're calling it now will be just as convenient. It's a bit similar in that the iPods were always iconic. I don't want to play up the status symbol angle because I think it's exaggerated; the point is that to many people an iPod was almost synonymous with MP3 player, and at least it was the default option. The same seems to be true with the iPad.