By that line of analysis, we'd expect a Whiggist regime to have optimistic propaganda with contemporary scifi being pessimistic because the Whiggist faction is ineffectual?
I also think it's why most contemporary sci-fi isn't resonating, but that's just my own opinion based on speculation. I have a suspicion that contemporary sci-fi doesn't sell well. They all present societies which have solved social and material problems through progress, or which are still solving them, critiquing an image of the Western world in the 20th century. None of them nab at any kind of biting truth relevant to young readers today.
Short story "Best Of" omnibuses are especially depressing for me personally. This is where I found some of the most mindblowing stories and concepts I had encountered when I was younger, and now they're essentially no better than tinder for firestarting. The people running the Nebula or other awards have astoundingly safe and poor taste.
What are some examples of scifi you're referring to there? Because the noteworthy scifi stories I can think of, ones which drew enough attention to be televised at least, are stories like the hunger games (dystopian), divergent (dystopian), the new star trek series (which I haven't seen but I understand shoehorned scarcity back into the startrekverse), Foundation (fall of a golden age), The Expanse (dystopian) etc. I think the only optimistic scifi I've read in the last twenty years or so was Anathem, and there's no way that's getting a miniseries.
Maybe it's a function of the authors I follow, but I just don't see this optimistic contemporary scifi you speak of, naive or otherwise.
The maximally unequal society of Hunger Games is resolved via a violent revolution in favor of more egalitarian values. Same with Divergent. Star Trek Discovery is about a sexually and ethnically diverse crew somehow (in a future that was supposed to have solved these things) facing bigotry and solving it by simply applying or arguing for the "morally correct" values they already have. In Foundation, enlightened technocrats shorten a regressive civilizational collapse and return to "upward" progress by literally tricking the surrounding cultures into the Foundation's value judgment of the "correct" path (very VERY State Department of them). The Expanse is a TTRPG novelization and subsequent TV adaptation where a near-literal paladin (Holden) applies enlightened egalitarianism, diplomacy, and pacifism to stop an interplanetary faction war.
ALL of the specific stories you mention feature extremely strong Whiggist storytelling, and further than that, Isaac Asiimov (author of Foundation) was a famously outspoken activist for enlightened, Whiggist, progressive, technocratic ideals. Many peoples' first introduction to these ideas was Star Trek, though modern Trek handles its themes with all the subtlety of a mace.
I suppose I might have been imprecise in my speech by conflating optimism with utopianism, but 'depiction of future I'd like to live in' and 'optimistic scifi' are close enough concepts to those of us untouched by modern English departments that those of you who are could just disambiguate and move on when you encounter it.