I can understand them not wanting you to access the GPU peripherals from the ARM processor, the GPU can handle out-of-order data access, but the ARM core cannot (although it sounds like you can get around it with some careful programming).
At this stage i'm happy we got anything out of them at all, limited as it may be. A datasheet for the GPU would be great though. But given the progress of Open Source drivers from the groups working with AMD and Nvidia (who are much more forthcoming than the embedded graphics vendors), I can't say I would prefer to wait 3 years for a functioning driver that can handle OpenGL ES 2.0 and accelerated video playback. You'll still need a binary blob in the meantime. And it's not feasible for them to just give away their driver source for free in the meantime, for the same reasons it was never feasible for nvidia or AMD to just open up their proprietary drivers.
I think in time the situation will improve, but you can't expect Raspberry Pi to reverse standard industry practices in a single leap and bound. Give it time, and see this release for what it is: progress.