The IP is locked out because there's an extra cost to the business to use it.
Also embedded/mobile GPUs haven't been around nearly as long as OpenGL ES. Heck the Adreno 2xx which was one of the first real-ish GPUs was released in 2009 and even then you'd be lucky to get any sort of reasonable fill rate out of it. These type of GPUs really haven't come into their own until the last 3-4 years.