Dr. Sevrin said:
DS9 only used them once, and didn't seem to have any interest in bringing them back, so it was probably best to let the film finish them off. Else they would have kept popping up to give Worf trouble on the station or something.
I don't know. It might've been nice to have kept them alive, to have kept the story going, and given Worf an opportunity to take them down personally (yeah yeah, I know,
technically he fired the Torpedo that killed them..... but that's not really the same thing, is it?

)
TNG spent quite a lot of time and effort building up the whole ongoing Worf/Duras storyline, and it seems a shame to me that they so arbitrarily finished it here. Mind you, when they made GENS, they had no idea Worf was going to move over to DS9 yet, so maybe they just figured it wasn't going to be something they were gonna need to tackle in the coming movies?