Bonsall's got it wrong
"I'm trying to think of another thing that someone could buy and reasonably demand full access to the thousands of hours of work that went into it so they could make sure it worked"
You think this is what open source is about? That's not what it's about. Without open source what we have now is this: If a software product were a coffeemaker, it's maker is, say, Braun, and I buy one, and I don't like how it makes coffee, so I modify it, Braun would sue me. If I put instructions on how my Braun Coffemaker Modification was implemented on the web so others could change their coffeemakers to work like mine, I would be thrown in jail. This is a set of laws written by pernicious people in the software biz who managed to wool people who have no idea what happens to anything once it has electricity running through it (i.e. Lawyers). It's a sick joke.
The model for the future you describe (that of an Application Service Provider) works great until data portability becomes an issue. Then everyone realizes that the last thing they want is to have a mission critical app hosted at an ASP. ASPs aren't all bad, but ASPs are not "the future". It's just one way to solve a problem that will not replace other ways.