It's probably not worth the time/resources for them to develop/port a decoder for such an uncommon audio format.
I know...as with VHS vs BetaMax and HD-DVD vs Blu-Ray, there's always a competing format that kills the technology. In this case, neither DVD-Audio or SACD were particularly embraced due to very few people having the system to take advantage of their superior sound--but SACD lives on thanks to classical music and of course now the standalone DSD format (as does technically DVDA with TrueHD). I still think DVD-Audio sounds better though in a head to head comparison with an album like Beck's Sea Change.
The main reason to keep them in the original format is for the extras that were sometimes included on the discs. If you aren't familiar with one its difficult to explain, but several of them had some cool inclusions (such as band interviews on the Grateful Dead discs). For me, it's also a cool nostalgic reminder of the early 2000s seeing the album graphics in 4:3 aspect ratio--and just playing them like i remember from disc. Since i bought up every single worthy one at the time totaling over 50 (now easily worth thousands of dollars on the open market), i really want to avoid putting the originals in to keep safe, but get same functionality. There's also some notable "home-made" ones created over the years you can find if you search. Again, that's what my ISO-playing Oppo 95 continues to be for...