At least most of them are... and I have believed for some time that they have damaged the industry. Nice to see someone agrees with me. There is an article here: “Unsustainable” – MicroStock Comes of Age…er, Not. that deals with the Micro Stock photography industry and explains why it is not all coming up roses.
I personally have never had the urge to sell my hard work for a pittance and probably never will develop that urge, but the Micro Stock industry has affected many hard working photographers worldwide negatively anyway. If you feel the urge to work for nothing, at least do it for a good charitable cause, not to simply enrich some jerk in an office a thousand miles away!