We now know there's significantly more on-the-record evidence that R.Kelly is a child predator than Michael Jackson was. This is unlikely to change either singer's respective legacies or reputations; the child sex allegations will continue to be a footnote in Kelly's career and a defining element in Jackson's. This is unfortunate, but it's also an opportunity to illustrate a basic concept of critical theory.
Critical media theory seeks to examine how the structures of power, specifically in mass communication, enforce cultural norms. That R.Kelly gets a pass for alleged pedophilia (recent attention notwithstanding) while Jackson continues, even in death, to be portrayed as a pedophile presents us a demonstration of the media's role in enforcing heteronormativity; the practices of institutions—in this case, the media—define human identity along the lines of discourse and cultural practices demanding heterosexuality as proper behavior and anything else as aberrant.
If you're looking for a "simple" explanation for why R.Kelly's escaped mass criticism for his alleged (and, in at least one case, admitted) predatory behavior, that's one way to go. And it's a simple explanation of how critical media theory works.