Ok, I often skip straight to season three when rewatching Enterprise. I thought it was a decent show overall, and I preferred the dark themes. Perhaps this is as simple as a perception difference? I can think of countless episodes in many Trek shows and movies where the optimism you speak of is simply, “we are optimistic we can blow these bastards out of space”. Indeed, in my estimation, the original series (and half the movies), Voyager, and Enterprise were all far superior to the candy sweet “can’t we all just get along” bullshit in STNG and DSN. Indeed, as far as I can tell STNG was the writing on the wall that pointed to the current state of affairs on Discovery. Sure, you are describing Discovery as lacking the optimism of STNG, but what they share is PC driven ethos that renders them useless. Bottom line, I will pass on Discovery, but I will also pass on overly optimistic sci-fi in general. Heck, what made the last two episodes of The Orville the best yet written? Betrayal, death, bodies, genocide, battle, etc. Yes, they won, but at a cost. The problem with optimism is that it flies in the face of reality...and ruins lots of sci-fi.