With the music industry brining in about 35-40% or revenues they used to not too long ago, before the CD sales started slumping, you better believe MQA will be a bandwagon most labels will want to hop on. It is another source of revenue for them to offer their music in MQA now and collect whatever they can from that. Musicians also need to get paid. It's not exactly what it used to be, not as easy to monetize their music when everyone expects FREE music these days.
No one buys CDs, many listen to music on youtube which pays artists/musicians a fraction of a penny, that's right, .006 cents per youtube click. Radio stations pay a different license fee and it's not a great source of revenue as many musicians give their music out for free to radio stations to promote it.