Music is distracting when you need to be creative, because your creative brain is effectively distracted by the music. I read about a study[1] recently that presented a programming problem to two groups; one group listened to music while they solved it and the other group had silence. While each group performed acceptably with regards to creating a solution that conformed to the spec, the music-listening group neglected to notice that a series of transformations in the problem spec turned out to result in no changes whatsoever. The group working in silence was able to make the connection and came up with a more efficient program.
[1] Sorry, can't find the source. Will update if I find it.
I don't disagree with your point, but the 'study' is essentially an anecdote about two incidents, in which the difference could just as easily be about the group members involved; I think one cannot draw significant conclusions from it, as described.
[1] Sorry, can't find the source. Will update if I find it.