I think its a good idea because in powder toy there is no sound which is weird. With that element we can hear music by just typing youtube id if you can.
TPT isn't the type of game that needs sound. It's not trying to be a whole interactive experience, it's just a particle simulator. Allowing people to put music or links to music in saves would be disastrous, just think of all the rickrolls and copyrighted songs that would be linked.