I don't have a TV so I imagine I am missing a lot of the all important media circus action on this one.
I never bought an MJ album, and I won't claim to be a huge fan, but if "really good music" in the "top 40 pop" genre means catchy tunes, he is responsible for a lot of really good music.
I do think that from the very beginning many of his songs were lyrically advanced from a poli-sci perspective and still sound that way today, so he could not help but "change the face of music forever". He also was a pioneer in the edgy, slightly dark and disconcerting androgeny of 80's pop. Altho it may seem ubiquitous or cliched today, the fact that it could now seem ubiquitous or cliched is an accomplishment in itself. Micheal Jackson did not end up a cultural icon for no reason.