Gene Roddenberry had a rule that drove the writers of Star Trek The Next Generation absolutely crazy: there can't be any interpersonal conflict amongst the crew. The result was a cultural product I consider almost unique: a story about good people trying to do the right thing that isn't boring.
These days, moral ambiguity, twisted anti-heros and an apocalyptic vision of the future practially comes standard in our stories. Dark and complicated is synonymous with "smart," but in fact it's probably ten times harder to write a compelling story about principled, competent and psychologically healthy people. Star Trek TNG dared to imagine a future for humanity where we outgrew our petty squabbles and became our highest selves, where we travel the stars fulfilling our curiosity and genuinely making the universe a better place.
Patrick Stewart's Captain Jean-Luc Picard was the indispensable anchor to this vision. Instead of William Shatner's campy swagger as James T. Kirk, Stewart's Picard made "tea, Earl Grey, hot" iconic. His depth and gravitas as a thespian specializing in Shakespeare sold the moral dilemmas that were so often at the heart of the best TNG episodes.
The dramatic tension in TNG comes from people sharing the same ethical framework as a group facing difficult problems. The buck stops with the Captain. He listens to and respects his crew, but ultimately it is up to him to "make it so."
For TNG to work as a show, Stewart had to take those very internal struggles between a man and his conscience and make it dramatic. He made Captain Picard's very moral seriousness charismatic. He made you believe that...yeah...of course there is a moral arc to the universe and it bends towards justice. Of course it is worth paying the price to stay true to our principles. And of course, the struggle to discern what is right action is actually much more interesting than wallowing in how broken everything and everyone is.
Bon Voyage, mon Capitaine