According to the article, and we bet you could have guessed this after listening to all of our own rants on the subject, it all comes down to money. Because the parent networks have more viewers, they can command more advertising revenue, and therefore it makes no sense for them to move first-run content -- like, say, "Battlestar Galactica" -- over to Universal HD where its ads will bring in less money for NBC. Channels like TNT HD don't face this problem, as they simply simulcast whatever is on the original standard-definition channel with the same ads and all. Of course, they also add some stretch-o-vision to the non-HD shows, much to our chagrin.
So, how do the networks manage to launch new HD content without affecting their meat-and-potatoes SD (at least for now) content? Universal HD, for one, is planning to have some live content, like the US Open, which can help bring in some viewers, and certainly adding first-run shows or more popular syndicated programming can help. Also, as more and more households throughout America and the world purchase HDTVs, these channels will most likely be folded back into their original networks, as the fact that they feature HD will be less of a novelty and simply something to be expected in programming. We can't wait to see 100% HD programming, 100% of the time, with 100% surround sound, and no stretching, no fake upscaling, and no pillarboxing (just kidding!)
[ Thanks Andrew Yoon ]