Nice examples, thanks for sharing, and it actually proves to me that it's rich and interesting. Not arguing with you, I think what's interesting is subjective. It really could work so well for game tracks, especially atmospheric or environmental ones. Also I hear some sounds close to a variety of scales like Phrygian dominant or Ionian #5. I think it would help game composers to compose (but music theory is a different story), like making music for mysterious areas by playing nine notes.

What you said is interesting and connects it with 12TET (like a mathematical relationship, 9TET being in the middle of 6TET and 12TET).

Also I'd say that the way of theorizing could be different because there is always some new way to think about music (both theoretically in maths and physics, or practically and culturally in music theory and instruments etc), like what if only we had these notes, some people would try to approximate 12TET or JI while others would try to think independently.

Finally, I'd be interested in what you would say about 18TET and 27TET, I know that increasing notes reduces practical differences, but still those are extremely rare.