I've heard a lot of covers of Bach's Brandenburg Concertos. Still trying to find a copy of the original, but they seem to be rare in these parts.

Seriously, if the OP is going to rant against those who sing "other people's" songs. Then why not take it up a notch and complain about those who play the same thing twice. I mean, if it isn't improvised, then it's not original.

Even more seriously, let's just concern ourselves with wherein the music lies.