The problem to me is the OP using the ethical loaded definition of free in one's choice of licence and at the same time referring to the use of copyrighted material (that is clearly in a bit of a grey area) is at least strange. (And the attitude of the OP is clearly a bit popcorn time. )

I like the app because the official clients tend to suck. But I am also paying for a lot of music previously downloaded from the sites. The problem I see with such clients is that if they would become popular they trigger reactions that make the web typically less free in any sense. But there is definitely better ways to support artist than streaming subscriptions...