there's a misconception behind this kind of revisionism (which okay admittedly i've done within the rock narrative, highlighting neglected by historians periods like postpunk) which is that history writing is like census taking or something, it's meant to dispassionately record what people "really liked"
it's not: history-writing is always partial, always partisan, it's arguing for a particular cause, it's invested in one theory or ideology, or on the side of one historical class... however much it might pretend not to be. certainly critical histories of the arts are.
so it's not the fact that historians have neglected or overlooked all these genres, it's the fact out of the masses and masses of people apparently into them, few of them were motivated later to write a history of them. the disproportion in the amount of history itself, that is the telling thing. and of course it relates to that motivational power that rock (and rap, and rave) possesses, the fact that it generated these incredibly energised discourses around itself, that pulled in the kind of people who'd later be moved to write histories of them.
Another angle on this: no actual Celine Dion fan would write a book as interesting and culturally-contextualising as Carl Wilson's book on Celine. It took someone who'd been through the rock-discourse mill, to have the capacity and the motivation (perverse as it might seem).