Why should any project have to justify it's existence? Maybe it just scratches an itch?
Unfortunately, unlike many of their projects, they don't seem to have a blog post yet for it.
It seems like a natural conclusion to spend a fraction of the energy to author, to detail it's reason to exist.
Anyway, no one owes me anything but I trust that Determinate Systems has a grander vision than I can see, I just want to be clued in, to be honest ;).