I think its likely familiarity. Licensing is legal terminology so anything new requires time to reason about. In this case I am a strong advocate for these licenses as they're written in part by Heather Meeker who has authored some of the custom licenses for Redis Labs, MongoDB, etc to protect against this cloud provider hosting issue.
Then I'd love for them to get some more attention, discussion and scrutiny in the community, because I think that's the only chance new licenses have at gaining wider adoption.
