I also know from experience in the mobile application business that Android Market is the easiest platform vendor or carrier-controlled app market to deal with.
My comments relate mainly to how the tablet business differs from the handset business. The same practices that might be necessary for Android handsets don't apply to tablets, and evidently don't work as well, either.
I think tablets will be a very big part of computing, and Android tablets should be a big part of the tablet business. But, so far, Google hasn't allowed many low-cost OEMs to ship Android-based products with Android Market and Google's other proprietary applications. Had Google gone with, say, Archos on a $350 tablet instead of Motorola for a high-end product, the tablet roll-out for Android might be very different now. More generally, Google should not have tried to pick a winner, or a winning approach to tablet product formulation.
That openness to all comers makes Android Market vibrant and diverse. Maybe Google should try that approach to tablet OEMs, too.
Plus, you get a choice of formats. Amazon sells only Kindle format e-books.