[Cadaverous Pallor]

Aren't a large proportion of films book adaptations? When I began work at a public library I was surprised how many films were based on bestsellers (mostly because I don't read much in popular fiction).

It's hard for me to say that taking a new novel (like, say, The Bourne Identity) and making a movie out of it is derivative or somehow worthy of scorn. Making a movie out of an older book may be more lame but I Am Legend is a situation I'd again be ok with, as the original book isn't super-well-known and neither is the first movie adaptation (which I hear is for good reason). There are always exceptions.

Anyway, getting back to your point, you're 100% right. We reward retreads, for obvious reasons.