I respectfully disagree. The average user has no idea what an OS is, or why you would update it. It's something they do, under instruction, because other people are doing it.

Good point. So, in the end, a user just expects all to stay the same?

Yes! :) While it's delightful if iPad suddenly does new things, it's not expected.

So why are they updating at all then? If they don't expect any change (either positive or negative) why are they doing it?

Because you or I or someone like us tells them they should for a new feature. Or they're fastidious. Or they feel like they'll screw something up if they don't. Or they do so in hopes of improving a poor experience. Or they pay attention to and trust their vendor's marketing. Or they take it in for service and its done for them. But for the most part it really doesn't mean anything to the common customer.

That's something Apple forgot in their skeuomorphic design of Notes.

People expect that when they get a new notepad their old notes will still be there.