Would like to note Picard DID choose to allow a race to die out once.
And in Season 2's "Pen Pals", after much discussion with the crew, he decides to not let the race on the planet die out.
Pen Palls is some ways even worse than Dear Doctor. "We must not interfere with the natural development
of primitive cultures, even if it meant letting them go extinct"... Yes, because when a civilization goes extinct, it continues to develop.