I'd like to suggest that dnstap should be enabled by default going forward, starting with bind914. Doing so would be a no-op for people who don't use it, since it has to be specifically enabled in the configuration. dnstap is much lighter weight than traditional query logging, so it benefits large and small systems alike. I suspect there may be quite a few people like me who would appreciate the ability to use dnstap without building our own packages and maintaining our own repos.
This would add a dependency on devel/fstrm and devel/protobuf-c, but both packages are tiny, and protobuf-c is a dependency of a number of other common ports.