May be you should take a step back first and find out what type of people get music stuck in the heads more than other people. That might be the key to it.. if those people are more creative than other people.. then it may possibly be a message from their subconscious telling them that they should be doing something creative..

Who knows.. but it sounds more of a sociology thing than a psychology thing.. so you have to look at the society rather than the person.. what is music? why is music? why do certain types of music sound better than others.. plenty of questions to answer.. :)