No. Have you even read any of the works I mentioned earlier? Science Fiction can no more be cleanly divided into two camps like that than you can say all of fantasy is about nostalgia for the past (or even that science fiction is always about the future, considering how big of a genre alternative history is).
I mean, there are
plenty of dichotomies you can use, as long as you recognize that these things are always a spectrum, and there will always be works that simply don't have a spot on the scale because it doesn't apply to them.
Consider Apollonian vs Dionysian, or "hard" vs "soft" sci-fi, or "hard" vs "soft" magic systems. All of which definitely
are terms that have existed for ages now and have generally understood meaning--and as long as a work is "sci-fi" of some kind, you can probably put it somewhere on a sliding scale of hard vs soft. That first one goes back to Nietzsche at the very least, possibly earlier, and drives at the very heart of what the author is trying to communicate; e.g. Asimov was inherently an
extremely Apollonian writer, while Le Guin was a very Dionysian writer. It's rare for a sci-fi or fantasy author to fall
entirely outside that scope.
Whether Vernian corresponds to hope and Wellsian to despair, I don't know. Doesn't seem the most relevant argument to wage, whether or not there's a solution waiting on the other side.
I do think that
@Remathilis is on the right track with Jettsons vs Terminator though. For all the follies and foibles and problems, the Jettsons live in a positive world where things can get better, and folks who stand up for the right thing, even if they aren't directly rewarded, know that they're contributing to that. For all its chrome and (after the first) action-packed resistance, the Terminator franchise is about a world doomed to face the war of Skynet vs Humanity;
even Skynet, the horror that will inevitably darken the future, is trapped, incapable of redirecting its future, and possibly even incapable of preventing its own demise at the hands of John Connor's resistance.
In breaking out of the limitations of modernism (which is what the Jettsons arises out of, ultimately), we've also framed everything in the darkest tones. Of course, that break coinciding with breaking out of things like the Hays Code and the Comics Code Authority and similar censorship schemes that enforced the atomic-family-white-picket-fence world didn't
help on that front. Positivity was associated with all the negative things that censorship brought with it: conformity, thoughtlessness, submission, hollow platitudes, designated "heroes" who look quite a bit less
heroic if even slightly examined or questioned.
But the unfortunate conclusion that was drawn from that was: Anything dark is
always superior to anything bright. Bright is stupid, naive, actually or unintentionally propaganda, censorious, childish, etc., etc. Dark is smart, daring, realistic, straight-talking, adult, etc., etc. Neither of these conclusions is correct, but
in the limited context of a world that was finally breaking free of a censorious regime, yes, it was true that adding darkness to stories was a great way to give them more depth and maturity. Because that was adding darkness to things so whitewashed there wasn't any color left in it. But "Add darkness, it makes things better" is a bad maxim when applied universally....and that's exactly what happened. It's been applied so universally, damn near
everything is dark now. Darkness is presupposed. Cruelty is presupposed. Stupidity, malice, cowardice. Every smile hides a dagger, every good word is a hollow facade.
That isn't any more realistic than the former state of things! But that's where we've ended up. Of course, just as the censorious BS of the previous era couldn't completely stifle
everything, the overwhelming cynicism of the current era can't completely stifle
everything either. That doesn't mean it isn't oppressively dark though. The new
Superman and
Fantastic Four movies were such a breath of fresh air because they, themselves, are deconstructing the deconstruction.
When power is wielded by the cruel, compassion
is punk.