Most of what works in the Star Trek movies evolve from what we know about the characters. Kirk’s love for his ship and history with the Klingons, Picard’s history with the Borg, Data’s struggle with emotions, that sort of thing.
What character threads from any of the series could have been picked up and expanded on in movies?
Yeah DS9 was a bit more ‘real’ than the other seasons I think. Especially dealing with some pretty dark stuff like the war and how it was resolved, genocide was on the table like you say. Hmmm. Does make the federation look a bit different when you think about this shady stuff being allowed by the top brass because it works in their favour.