I don't share Declan's antipathy vis-à-vis Star Trek, but his insistence on world building and good characters is certainly on point.
Good science fiction requires two things: good world building, and good characters.
Obviously, all writing requires good characters, but in the world of SF, the world and the characters are interlinked. The world created by the writer is going to shape the characters as much as anything else.
Let's look at why the original Star Trek worked, shall we? While the Federation wasn't as well
developed as it would become, most of the places the Enterprise visited had fairly simply ideas behind it, but you could see how that worked. Even if it included Roman Imperial Nazis, or a world run on the model of the gangs of Chicago. They took simple ideas, made a world around them, and tossed in their semi-iconic characters, who are all perfectly likable, into the mix.
Then you go into Babylon 5. It had a deep world in the background, and that's evidence from the
various and sundry guide books for role playing games. It it depth, it had science that obeyed the actual laws of physics. It had politics – and none of this Utopian, one-world BS of the Federation. Star Trek was one big happy fleet, while B5 had opposing views and opinions, and hate groups and civil war, without the aliens fresh from Mordor. Even at Star Trek's deepest, they had, what, three episodes of DS9? The Maquis? Who, on Voyager, were assimilated by the Federation after one episode and half a season? Even the Klingons, at their worst, had a bought of internal strife that lasted for ... an episode? Three? B5 had a year and a half, if not three (depending on how you count it).
The best science fiction has a whole range of culture and society, as well as spiffy technology. I believe it was Sarah Hoyt who pointed out to me that SF has two core tenets: either it's hard SF, or cultural SF (much of which is owned by SJWs). But what happens when you have someone like John Ringo or David Weber, or a Babylon 5, who cover science, history, technology, culture, economies, and how things get done not only from a technology aspect, but also a governmental aspect? Star Trek really never had a history behind it until later, and none that was ever really felt during the show, and made up as they went along, and we won't even go into whether or not they don't need money (as Troi once told Mark Twain) or if they operated on a system of small gold bars (DS9)
Heck, when I wrote Codename: Winterborn, I went through a lot of trouble trying to apply all of these lessons. A lot of it was so easy, I'm surprised more people don't do it more often.
When my co-author, Allan, first mentioned his world to me, before I even signed on, he had a simple
premise: the world had been nuked on 4-1-2090, with San Francisco cut off by miles of wasteland from the “real world.” From there, a lot of it was easy. I just asked questions. And what he didn't know, I reasoned.
What's the economy? For San Francisco, locally, it's a barter system. However, since the larger corporations still have connections to the outside world, money is still good. Why would corporations be in San Francisco? Because there are now no limits on off-coast drilling. Duh!
What's the history? Allan wanted Israel to take over the Middle East in the 2060s. From there, I created the Bethlehem Catholic Church ... because Rome was nuked when everyone started breaking out their own atomic toys. And since the Franciscans were long ago given places of worship to run in the Holy Land (this goes back to Saint Francis), Bethlehem sounded like a great place to move. Yup, the Catholic Church. We're like roaches. We WILL survive being nuked. You can't stop us, you can't kill us. We'll always come back in three days. MUAHAHAHAHAAHA....
Also, when I did the math on anti-ballistic missile systems (which are already up and running, by the by), I figured that Allan's United States would only be partially nuked. But that would certainly take a good chunk out of congress.
The nuclear war led Allan to create San Francisco, but I figured “So, there's a real world out there, right? And the real world has satellites, right? Well then, that means the rest of the world knows. World governments know, if nothing else. This makes San Francisco a great place for dropping off the inconvenient of their population. Why kill them when you can just be rid of them?” This created Exiles. When I suggested making a spy to be dumped there, Allan said “I'll call him Mister Anderson, like The Matrix.” He became Kevin Anderson.
But what horrible, horrible sin could Kevin commit to send him to a little backwater hell? Something to do with a mission. Do I know any places that'll be the enemy in 2093, since the Middle East will be run by an ally?
Oh, wait! I know where all the remaining Islamofascists will be! Europe! Let's make it France! (Whose birthrate in 2003 was less than half that of the fringe elements who tended towards radical Islam, meaning that by 2050, France might just be the Islamic Republic of France). You can see how the progression goes from there. After a while, and after enough time, the world writes itself. But in order to get there, a writer has to bring something to the table. A worldview, a knowledge of how the world works (either theirs or the real world), and it proceeds from there.
Good science fiction has depth, of both world and of character. The world building can be cultural, technological, or both, but there's got to be something there that warrants it being a tale of science fiction. But most of all, the characters must carry it. If it doesn't, then the writing just sucks. I'm not going to read books about technology. I never even read the Star Trek technical manual.