What does DNG have to do with the usefulness of DxO Optics Pro as a Premium Application for processing raw files from digital cameras.
DNG is the product of Adobe and it has many benefits which users of Adobe Products can take advantage of in their workflow. Not necessarily so for people who use other software to process their raw files that may or may not provide support for DNG files.
If you have painted yourself into a corner by converting your photo files to DNG and have not retained your original raw files produced by your camera, so you are unable to use software applications that do not support DNG, then that is your choice. DNG is not an adopted standard format, despite having been actively promoted by Adobe for over ten years.
Most of the major camera manufacturers (Nikon, Canon, Panasonic, Olympus, Sony, FujiFilm to name a few) have completly ignored its existance and the software they provide also do not support DNG.
This link provides a fair assesment of the current situation. http://members.lightroomqueen.com/Knowledgebase/Article/View/1159/183/should-i-convert-to-dng
I for one use Lightroom as my main processor for rendering my raw files and I am pleased with the performance. I am particularly please that all the work that I do on my files is stored in the Catalog file so I have no use for "sidecar" xmp files for storing data. If I need to send files to Photoshop for additional work I use the "edit in feature from Lightroom".
I also utilize a few other raw processing software applications on occasions, some of which do not support DNG. As a result DNG has no place in my workflow, to me it's like the proverbial "Tower of Babel" from the Bible.
At this stage I think DxO and Capture One have leapfrog-ed Lightroom / ACR in terms of the quality processing of raw data. I expect this to be corrected with the release of LR 6. Competition is what drives the development to the benefit of the user.
Hey this is why I retain my original raw files to benefit from superior processes in the future.