SpongeBob [and The Simpsons] definitely played a role because of the wide variety of music they used, especially in the former [The Simpsons used some stock tracks in addition to the vast input from Alf Clausen]. SpongeBob helped make "Cha Cha Nova", "Sweet Victory", and "Andy Anorak" well-known pieces*, and playing them in new arrangements always makes the audience perk up.
My discovery of library music coincided with my interests in music, technology, and history - here was a way to arrange music for performance and re-recording, appreciate the medium on which it was first recorded, solve a mystery or two, and learn background behind the most fascinating music "genre" in the world. I've never particularly liked modern commercial music as it is, so I found the vast array of library pieces infinitely preferable to what pollutes the airwaves, due to my non-mainstream musical tastes.
*okay, okay, okay, I get that I made a non objective statement
Genre might not be the best term, but it's the only one I could think of...though library covers a ton of different musical styles.
That coalescence of music, technology, and history also explains my constant questions about [seemingly] random Eastern Bloc vinyl