Mainly because everybody involved knows, at least on some level, that this is a game. Also, carrying through to the point where Bond wakes up, takes the microfilm and leaves is going to involve at least some camera-dissolving in all but the most liberal LARPing groups. Seduction can be difficult , at least for some players. Not everybody can be as good with a rapier as Zorro. Unless you want to limit casting Cyrano de Bergerac to only those players in your group who are universally found supernaturally charming to everyone else in the group, some kind of mechanic is probably a Good Thing.
Seduction can be less fun .
Ok, it's not a universally applicable example. With seduction, it's hard to be fair . Here's the gist of the thing. If character A is trying to seduce a piece of information out of character B, the success or failure of the thing is entirely in player B's hands. Nobody likes to give up control, not to mention microfilm.