That's apples to oranges. Pandora and Spotify pay artists per spin; the more you play, the more you're paid. Apple paying a percentage of revenues is an entirely different method, and it doesn't explain how that money is distributed. So, it isn't clear that Apple's ways are any better (or worse) than what's already happening. More information about the theory and reality of the payments is needed.
I get your point about Apple Music being otherwise 100% paid and now eating the cost of a free trial, but the alternative was _artists_ eating the (opportunity) cost. That's not very nice, especially given that Apple can afford it.
Besides, holding up Apple against the behavior or record labels, movie studios, and game companies - that's a pretty low bar, honestly.