More tracks in the list is fine.
Just I wouldn't expect too much change by making the list longer.
I remember tracks karma went down pretty steap towards place 20. So a track on position 40 will have not much karma left to fight for. ^^
I don't think all tracks should get karma automatically. That would make the playpal system kinda useless.
It's there for the players who want to fight for karma in order to get their tracks played.
And as we know, the most terrible tracks often have the highest karma because noone fights on these tracks.