Hmm... OK. Interesting, your idea.

Your writing seems all good and fine. I see correct useage and well-formed sentences and paragraphs. I have issue with your content, however, and while I'm sure this can be taken as merely opinion - and feel free to do so - I know a thing or two about music genres and "rock music" myself.

You go as far as to call the 80's a sleeper time in regard to the fact that no influential rock music came from the era, going as far as to even quote the infamous Buggles video, yet you completely ignore the very style of rock which that band represented, which was alternative rock, the most influential genre, that and punk rock, of the era. You've totally bypassed The Clash, The Alarm, Elvis Costello, U2, Duran Duran, The Beat (or The English Beat in the US), who were the very first Ska/rock band. I could go on... You call the 80s a time of downward freefall, and that could not be more far from the truth. Maybe the hard rock/glam metal scene had gone all show and no talent, but that, by far, does not constitute a decade of music.

Also, for the 80's... you have also completely bypassed the major influences of the "real" metal genre, bands like Iron Maiden, Judas Priest, Megadeth, The Cult, Dio, Ozzy, etc... these bands were VERY influential during the era, and still are to this very day. If you are going to mention glam metal and the "faux" metal bands, don't you think it would be good to make note of the real ones, too?

And you categorise Creed as nu-metal? Yet don't mention Linkin Park? Umm...

I get what you are going for here, and it COULD be a good idea, but if this is what you plan to base your entire book on, I strongly suggest  you learn more about what you are writing on. Either that, or somehow specify in your writing that you are speaking only of certain strains of rock and metal and not all of them (not sure how you'd go about doing that, though), because that makes this all misleading, and seem really unresearched. Even if this first piece is nothing more than an introduction, there are ways to make it read much more thoroughly than it does. I generally find this whole piece to be basically unfulfilling and unreasearched.

Please do not understand my review as any kind of personal attack. I am merely pointing out what I am getting from what you wrote, and I am sure your intent is to improve. In that case, I hope I can help point you in a better direction, or at least point out that the subject matter - from this point in the writing - seems lacking. Feel free to message me if you would like to discuss it further, or tap my brain for other ideas.