Pessimist the Sophisticated Intellectual, Optimist the Gullible Airhead.
For as much as I love the system apocalypse stories and isekai reincarnations, I can't get over how many stories portray their MC as intelligent because they are pessimistic or simpleton because they are optimistic.
Intelligence isn't a bane, it doesn't make you see the truth and become a pessimist. Meanwhile, someone can be optimist only because they are oblivious to the present, inexperienced of the world and that when they finally grow up, they will see how stupid all that is. It really gives that "I am 14 and this is deep" vibes.
At that point, all I see is a world continuing that cycle of pain. They drip of that same condescension as "Back in days, we used to do X. Youngsters these days can't even do Y." or "Oh you think that is tough? You don't know anything yet.". Intelligence isn't just narcissism and cynicism. What you describe is a low IQ patronizing wastrel.
And then you have optimistic MCs who are always shown as foolish, blind or straight up naïve. And the story just constantly tests those of them, either retaining those traits or morphing them into pessimistic intellectual. Either is irritating. Someone can be academically intelligent, socially aware, politically perceptive and practically knowledgeable but still chose to be optimistic. Still chose to believe in the good of humanity and others, while staying cautious of backstabbing.
And for that matter, readers are a huge reason for this mess. I have seen so many readers bash on optimistic/heroic MCs for failing, slipping or taking the inefficient choice while many readers just accept pessimists as pragmatic, ruthless or world-wise.