I feel the opposite, actually. As great as Wrath of Khan is, the conflict was basically manufactured for the purpose of the film, and really only has a tenuous link to the events of Space Seed. By the end of that episode, you'd never guess what Khan was going to turn into. They had to add an exploding planet to the mix off-screen in order to arrive where they did. The events of First Contact have FAR more connection to the previously established plot threads of Best of Both Worlds. You can see the effect that the Borg had on Picard in episodes like Family and The Drumhead, so the central conflict doesn't come out of nowhere.