...as far as continuing the plot threat from "The Defector", I can't believe TNG dropped the ball on this.
That last line from Picard, about someday bringing Jarok's letter home to his family...
And then Picard GOES to Romulus after all and NOPE... nothing about Jarok's final letter.
Even a throwaway line about it would have made a huge impact, at least to me. Would have been a great epilogue to a great eps "The Defector".