I can see different aspects of this, claiming I almost fully agree with Torax's statements above.
It would be easier to tip the DJ straight for what they do, show them how much you appreciate their time and effort. Though you never go to a club and pay the DJ anything, they get tipped out or paid by the organizer. Sure the later makes things more complicated but that is why you have managers/organizers for events and they are keep honest by the want to do more. No DJ or entertainer will work with some one again if they feel ripped off.
As for the builders we have several that spent a lot of time making very nice rooms, I can imagine the how they would feel if some one DLed their work and turned around to make a profit, this will probably kill the free rooms being offered. I know if I built them I wouldn't any more for free. Though I would hope any one that makes a profit from them would in turn give a decent amount to the original builder, more so if they just open the room and AFK for profit.
I can see this as a win for big event organizers that manage them properly but its not going to be all win. Would still like to see this option directly on profiles so people can show direct gratitude and hopefully if you DL a free room you give credit to the builder.