I think it depends on who the artist is. For the most popular the artists wouldn't be complaining about being paid too little.

Either way if a formula change, distributing earnings based on an individual user instead of the whole pool, means the popular songs would earn far less.

It also means if someone listens to one song that would earn more than someone who loves music and pays the same thing!

I would argue the formula isn't wrong its difficult comparing an total Audio CD sales vs a lifetime NPV of music played on Spotify for an author.