Come on. Who said DD+ is "better"? The audio master's from different performances are most likely to have the biggest quality differences -- that's the point people were trying to make.
With only needing a few still pictures and the disc focused on providing sound there is very good rationale for using a lossless format. If for no other reason than to eliminate the user's fear of audio compression artifacts.
I have Uncommon Mozart in hand. I am able to enjoy it now with the 5.1 core dts. Someday when I upgrade my AVR, I will be able to use lossless 7.1 dts-HD MA when playing it on my XA2. It will be interesting to hear just how subtle or not the difference is.