I never proposed different kinds in the context of NIP-29, and I think I have retracted my proposal for different kinds in NIP-72 too, but now I don't remember what was behind that anymore.
I've been thinking about having all sorts of kinds under NIP-29 and I think it all fits. The kinds 9, 10 and 11 are described in the NIP because there was no generic chat kind message anywhere else; and kind 1 is already too loaded so it made sense to make a new one. All other kinds should be safe.