Consumers will want that their new media hub is able to play BD movies
Consumers don't want to pay for hardware (and software licenses) they are not going to use. I never watched a DVD on my PS2, I had the DVD kit for the original XBOX and watched one movie on it. I have never watched a DVD on my 360. I haven't bought a physical disc in 1½ year, all the while having rented 50+ movies from various video on demand services.
Physical media is in decline, even as BluRay is overtaking DVDs. On top of that you have Microsoft wanting to push their own online media service, Zune. You've also got NetFlix.
Now, they may have a SKU with BluRay support, or have a SKU with an optical drive, which physically supports BluRay, where you purchase the necessary codecs/licenses on their app Market to get BR support.
Cheers