Aside from simpler billing, this would also encourage innovation in the tech space separate from the content space.

If I develop a service with a clever new gimmick-- a better recommendation algorithm, a clever social feature, improved accessibility, whatever, it's dead in the water today due to no content. I have to sell out to a big player to have any chance at traction. If I can just pay for a compulsory license, I can focus on the thing that makes my offering unique.

I also think compulsory licenses might provide a desirable social benefit-- separating the artist from their work in the public's eye.

Look how every election year you get the songwriters beefing and suing "I don't want campaign A playing song B". If everyone knows all content can be compulsory licensed, the air of endorsement is gone and nobody has to get inconvenienced or angry.