The name Scrobble Life implies that the project ties together all the types of content published by the site. There would be no harm in tying everything together (especially considering the points you yourself have already raised, which are quite important).

However, this community (albeit small, at least for now) is already becoming a go-to source for posts about movies and TV series (at least when it comes to reviews). Personally speaking, when I want to talk about cinema (in general), I use the Movies & TV Shows community to post something.

So, I would vote to keep the Scrobble Life community limited to reviews of movies and TV series only. As for the 10% "fee"... I really don't see any problem with it. That seems like a valid approach to help the project grow even further.

You're doing a great work with this whole project.