>The introductory films they show were simplistic and silly.

Sure, to someone who already knows their rock history.  But on any given
day, you have to figure that there are people going to the Hall of Fame who
only know a little bit here and there, and even the most simplistic films
will prove educational to them.

>And there 
>doesn't seem to be a coherent sense of what Rock and Roll even is...Britney

>Spears?

I suppose it varies from person to person how rock and roll is defined.  I
don't know that I'd lump Britney into my definition, either, nor do I know
what jumpsuit of hers is on display, but I know I've seen a picture of her
wearing some semblance of Elvis's sequin-covered Vegas outfit, so it at
least shows some sense of rock history.  And, hey, if some 12-year-old kid
comes to the Hall of Fame because Britney's jumpsuit is on display, and it
leads that kid, incidentally or otherwise, to discover Chuck Berry, Jerry
Lee Lewis, Little Richard, and so forth, then, hey, thanks, Britney...