From what I have seen, Roon devs are not willing to create a solution that creates a situation where there is different performace/specifications between different sources. In effect, setting up a second class existence for some source content.
Danny mentioned export issues, deletion issues. But, but album identification and other processes would also have to be modified.
If Roon were to tackle ISO handling, and to be clear they haven’t said they would not, I suspect that it would have to be up to a level of the rest of the software. Meaning, just adding playback alone probably would not happen. The solution for the other issues concerning ISO would also have to be addressed at the same time.