Just a guess, but it's possible that the Wizard of Oz theme might have been picked from the list because there is a very successful recent slot machine that used that theme. The close ties with pinball/slots being what it is, that might be part of it. Also, here in the US the Wizard of Oz is probably more "home-grown culture" than other countries. It plays on TV every year on some holiday (I think Easter?) and everybody is familiar with and fond of the story. As for me, growing up and living in Kansas all my life (though in the "big" city rather than rural) it is probably even a little more appealing.
There's something to be said about choosing a classic theme with a wealth of iconic visual, musical and sound sources to choose from instead of gambling on the latest "blockbuster" movie. Remember that TZ was just kind of a cult TV program theme and it was one of the most successful games. Addams Family was a decent, goofy movie, but that's not what made the pin sell how it did. The pin was successful because it was a well-executed game - not because the theme was something that folks just had to have. Plus until a movie is complete and you see it, there's no way to judge whether it is actually any good or just another marketing flash-in-the-pan that will be forgotten in a year or two. As you know, these days movies are very rarely any good. Even Avatar was just so-so overall (great visuals, lazy story and music) though it was billed to be a quantum leap. Bands have a much narrower audience to appeal to yet.
Anyways, in my opinion Wizard of Oz theme was a solid choice and it's likely to be a darned good machine. Movies might be a crap shoot, but with the cast of characters involved in making this game I don't see how it can fail in the "fun" category. Whether it's a business success or not we'll have to wait and see. I have a pretty decent job these days and I'd really like to order one for myself, but it doesn't fit into my budget yet (maybe next year it would have). It's true the general economy makes it tough to bet on anybody spending money on your product. IF I had it, I'd blow my money and order a Wizard of Oz machine. I don't have it currently though and will just have to play somebody else's. I still have a few quarters.