@AndyC: Even if you went direct, you would still have to pay all kinds of hosting fees, and figure out a marketing strategy that aligns with your direct sales model.
You have to do this with WinRT apps as well. What is the impression here? That once you publish something on the Appstore, your app will be automatically a success? That Microsoft will hype your application for free?
This may work in the early days of Win 8, but if Win 8 becomes indeed successful, the appstore will be flooded with apps and your program will drown in the app flood.
You need a marketing strategy and a website to promote your app anyway. And now, with the forced appstore, you can't just sell your app on your website (which you still NEED to have to promote the app), together with all the marketing and hosting fees you need to pay Microsoft an additional 30% cut, too.
Sucks. The appstore as such isn't the problem, the FORCED appstore sure is.