Just had a thought...

Here is a list of my favorite songs in MLP (not in any particular order):
This Day Aria
All of the Sirens' songs
The "happy Hearth's Warming" song from the Scrooge episode, and the Luna song from the same
Smile

Notice a theme here? Well, there are two: first, they're all well-composed, with good lyrics, strong, clear melodies, and more often than not several lines of instrumental under the melody. They're good songs; not much more to say about that. In fact, they're the best songs in the show from a musical perspective, especially in contrast to songs like "Art of the Dress" which, while a strong character show, is lacking in poetry and a cohesive melody. I am a very musical person, and a poet--it only makes sense that I like these songs best. But that's not what I'm here to talk about. The second theme in this small group is that these are mostly villain songs. I think it's interesting that, for the most part, the best musical compositions in My Little Pony are the villains' pieces.

I don't know why. I just thought it was worth pointing out.