I love musicals. Like, a lot. I'm mean, I'm no theater kid, posting Playbills on my walls, but I like to watch them and listen to them. There's something I've noticed a lot of musicals have in common.
The villains get great songs. Anytime a character does something evil they get a great song. Some examples:
Oogie Boogie's Song - Nightmare Before Christmas
Blood in the Water - Legally Blonde
Rogues are We - Holy Musical B@man
Mother Knows Best - Tangled
Brand New Day & Slipping - Dr. Horrible' Sing-Along Blog
Be Prepared - Lion King
Kick it Up a Notch - Starship
What You Feel - Once More With Feeling
Cell Block Tango - Chicago
I'm sure there are more examples out there, but this is what I came up with quickly.
By the way I'm not saying that the heroes get bad songs, just that the villain's songs tend to stand out.