Worf steps down from Klingon Ambasador to the Federation to be a security cheif again? What? There was no need to do that in NEM. They could have had him bringing a personal message from Shinzon to Picard as a way to bring Work into it. Once we got past FC it was misfire after misfire. What the heck happened? I blame Rick.
Dorn's new contract for DS9 specified that he could still be a part of TNG movies. Writer John Logan was faced with putting Ambassador Worf as a guest at the wedding, or he could put Worf back in Starfleet, all via a few strokes of his keyboard. It really didn't matter for the film, just that Worf be in it. So he rang Michael Dorn. He asked Dorn, "Do you want to be in your ambassador's robes?"
Dorn answered, "No, I want to be in my spacesuit - like everybody else."
As so ended Worf's sojourn as an ambassador.
This was part of a "Starlog" interview with Logan, IIRC.