Why haven't more freely-licensed databases taken off in general? For movies, IMDb (Internet Movie Database) is hugely popular and even lets its users edit, but its data is proprietary. TMDb (The Movie Database) provides an API, but its data is also proprietary and there's no way to download the data for offline use. OMDb (The Open Movie Database) has an API and is licensed CC-BY 4.0, which is great, but also doesn't provide data dumps. Can you really say it's an open database if users cannot redistribute your data or fork it? (Not to mention that the users are the ones contributing most of the information)
What gives me hope though is that two databases you mentioned are freely-licensed and do provide data dumps. This is essential for programmers to be able to create things that rely on these databases. We need to establish more free data stores, because as the article mentions, data is very valuable, and as the Wikipedia links show, proprietary databases have absolute control over their terms, restricting and locking out competition at any time.
Musicbrainz is the db you are looking for. Not sure exactly why it hasn't taken off like IMDb but movies and music and the kind of questions we ask about them are very different things.
I have home SW that accesses TVDB.COM to get fan art, descriptions, etc., for tv shows. Lately I have been getting 403s for requests. They won't say but I assume they are getting takedowns for their metadata.
https://en.wikipedia.org/wiki/CDDB#History
https://en.wikipedia.org/wiki/Gracenote_licensing_controvers...
Given this context, surely the article should at least mention http://www.freedb.org/ or https://musicbrainz.org/ ?
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Edit: Added musicbrainz