I think you are mistakingly comparing a closed system like the iPad to things like automatic transmissions. Of course not everyone wants to do lots of personal maintenance on their stuff or have lots of customizable features. But that's not how software development works. Everyone doesn't have to make their own software. A small subset of people create software that the rest use.
That's a good point that goes a long way to proving Apple right. Yes, a small subset of people create software that the rest use. And every day, that small subset desides what that software can and can't do. Apple decided what their software AND hardware can and can't do, because they make both. Apple never promised the world that all their hardware would be able to run arbitrary software.
At the end of the day, for the layman, non-techie user (ie: most of the population of the world), whether they are buying Windows, or an iPad, or using a Web app, they see it as something that enables them to do certain things and not others. They don't see the same restrictions we see as developers, and most of the time, they either don't understand them or don't care. At the end of the day, they got the product they paid for and use for what they wanted. If you want something different, buy something different.