Consumers would complain if they bought a Blu-Ray and there wasn't any actual HD content on it. They expect there to be some HD on it, and rightly so.
And as I said, since releasing the shows on BR would have exactly the same results as playing the standard def DVDs on an HDTV, then what would be the point? Just to save a couple of discs? That would not justify the expense. Having TNG, DS9 and Voyager (as they are now) on BR would not be the latest OR greatest; it would be *exactly the same*.