Well 80s rock doesn't really seem important by itself, but placed within the larger context of society and music, the 80s was an important set up for the 90s. 80s rock was riding the cultural and economic boom from the 70s. People reveled in what was once the social taboos of sex, drugs, and rock 'n' roll; it was a decade long celebration because people thought they had finally won in terms of the social revolutions of the previous decades. Finally, no more social barriers! Life is good! But then the harsh realities of an AIDS epidemic and a continued social inequality for minorities came crashing down. Welcome to the grunge era of the 90s.
It's practically a 180 degree turn-around for music, to go from the high-flyin', life is good, feel of Guns-n-Roses and Van Halen to the harsh rhythms and low-key beats of Garbage, Nirvana, and The Smashing Pumpkins. And it's important to have that knowledge in order to understand why the culture turned so grim despite continued economic success.
So yeah, there's no real "dramatic" story you're gonna find in the music scene of the 80s (apart from probably the typical "can-he-make-it" story), but then I get the feeling this really isn't supposed to be a drama. I think this movie is supposed to be what the music of the time was supposed to be: one big party.