Question is, should music be strictly a career ordered by the omnipotent overlord? I don't agree with Toady's notion that engravers should have absolute artistic freedom but he seems to think it's mind control. How about this then? Should the player be able to force a dwarf to play an instrument?
Now, this would be really unreliable gameplay-wise but I think people should only play if they like an instrument. Whether they want to publicly perform should be affected by their personality. Loners aren't gonna want to go play in a party even if you want the happy thoughts. Should you be able to treat his artistic tendencies as just another resource akin to a waterfall in the dining room, overriding his desires entirely? I'm surprised if they'd play it for their lover at home. That'd actually be pretty cute
So yeah, what measure is mind control?
The same way that the overlord can order a dwarf to smooth and engrave stone (through job preferences), the overlord should be able to order music. It would be a job, like engraving, and they would go on-break for it and such. Hopefully the system would be detailed enough that they would be able to sing about things, and the overlord wouldn't be able to control that. Then, dwarves could get thoughts based on the song and whether they liked it or not (so, a musician singing about purring maggots would give negative thoughts to dwarves who hated purring maggots).
If you were talking about musicians playing in their free time, though, I'd agree that that should be a dwarf-controlled activity. I would also probably expand that into storytelling and such, and have it be something that a dwarf with the right personality would do (friendly, likes crowds, etc.), regardless of whether they had a particular fondness for an instrument. If they did, though, they might demand that instrument to play on.