Fake your way to the top!

I am viewing my collection of CDs and DVDs and am struck by a revelation.

Why is it that the movies that feature fake bands almost always have better music than most real bands out there? I have the soundtracks and/or the DVDs for these movies:
The Blues Brothers
This is Spinal Tap (don't know how to do the umlaut thingy over the "n")
Josie and the Pussycats
Ladies and Gentlemen, the Fabulous Stains
O Brother, Where Art Thou?
Dreamgirls
Almost Famous
Edgeplay (well, technically, the band was prefabricated but the grls did have talent--OK, I'm stopping there before I launch into the history of the Runaways)

I swear, all of these soundtracks are on my "most played" list on my computer, and I've probably worn out the DVDs for most of them! Most of the stuff on the soundtracks is pretty basic. Everyone knows "And I Am Telling You I'm Not Going" from Dreamgirls because it's a standard, and "Cherry Bomb" (from Edgeplay) is a cult classic. And even I (out of practice and all!) could probably best Rachael Leigh Cook in an axe-off, since the riffs are pretty much all three chords. But seriously, it's still some catchy stuff out there and to me, a lot more fun and catchy than most of the stuff on the radio. Now if only some of these bands (with the exception of the Runaways, which came, sang, and conquered the Japanese market before dissolving) were real ones.

A grl can dream, right?