A lot of music could be said to be broadly international and possibly wouldn't benefit much from a country tag. I can't see a big win from tagging questions about Justin Bieber as 'canadian' or 'canada', for example.
However, as per DVK's comment above, I think there would be some value in allowing people to filter down to, say, Russian or Indian music (which might include questions needing more 'regional knowledge' to answer).
Just to address Dom's comment :
Genres are much more descriptive about what type of music a post is about then the country of origin.
That's clearly a true statement, but I'm not sure that everyone comes to the site with the intention of focusing on a specific type of music. I'm interested in learning about Korean culture for example, and am therefore interested in seeing all questions about Korean music, regardless of actual musical style. I'm not actually Korean, but I imagine that if any real Koreans come here, they too might want to look at questions that would be likely to be in their area of expertise.
So - I would recommend a 'neutral' approach to country tags. I don't think there should be a frantic effort to go around adding country tags to every question, but I don't think people should go around removing them either if they have been added and seem appropriate.