What is useful is really much less relevant than whether there’s anyone who wants to work on the project. If someone stepped up and said they wanted to work on “MovieBrainz” or “(Video)GameBrainz” or whatever, we’d be happy to help them. Someone did step up and wanted to make BookBrainz, hence BookBrainz is now a thing. Even though we have big name corporate supporters, MetaBrainz is not itself a big corporate enterprise, so as much as we’d like to be able to direct the future of what projects we have, it really all depends on whether anyone in the community actually steps up to take on the tasks.