Here, in America, there have only been a handful of TV theme songs that actually made it to radio (the theme to 'Friends' comes to mind), but in Japan almost every TV show's song comes from a hit artist - the equivalent of a Justin Timberlake, Beyonce or Boys like Girls here. Then the song goes on to become a hit.
Much like high school girls don't like wearing the same prom dress, I like having ringtones that nobody else uses. If I'm at Hastings and Low by Flo-Rida ringtone plays, 5 or 6 people check their phone to see if it's there's, but if 'Ikenai Taiyou' by the Japanese pop-rock band 'Orange Range' plays, I know it can't be anyone elses.
Have you heard my ringtone when you were with me at a remote (or Hastings)? Here's the music video for it.