I have a standing policy to tip musicians who play in public places (provided that I like the music). I like to encourage the arts, and it makes for a nicer experience while waiting for a train or enjoying a tea or whatever. I extended this policy to CommanderROR, because I like Bach and I like violin music, and this seemed to be the equivalent of a public place. If he wants to use this money to take his GF out for dinner, I'm all in favor.
That being said, I probably can't afford to do the same for everyone on MobileRead, even if you all suddenly become professional-quality musicians and post your work here. But I figured I'd explain my reasoning.