I think the problem is that most people don't know the difference and don't care.The average
guy puts the disc in and presses play,a lot of people don't even have surround,pump it to the tv and thats it.
I pick DTS when available but if its not there i am still going to buy the disc.I find that DTS has more detail and a better sense of air and soundstage but is also a little louder than DD.
Of course with Bluray with uncompressed pcm things have gone to a new level.

bill