Unfettered or Fettered: GMing styles and modules

"Before I learned how to play and GM with gamebooks and RPGs, playing pretend was testing whether you could deal with X, and ALSO was telling a story, AND the story had to make sense - that includes not violating what I know of munitiae like sword swings and your state of mind when someone is trying to push a blade into your skull*.
When I learned gamebooks, and later RPGs, I discovered the Three-fold theories (both of them!), and suddenly the game EITHER was about what you do to deal with X, OR about telling a story, OR about respecting and exploring munitiae like sword swings or conversational tactics, or whatever.
Now I understood Unfettered GMing, also known as Lazy GMing, and I'm just running a game that explores the munitae of details, and that produces a story, and people at the table treat it as a game."
Asen R. G., your host

Ok, that was a rather clumsy way to paraphrase well-known sentence ("Before I learned martial arts, a punch was just a punch and a kick was just a kick. When I studied martial arts, a punch was no longer just a punch and a kick was no longer just a kick. Now I understand martial arts, and a punch is just a punch and a kick is just a kick." - Bruce Lee, who was in turn paraphrasing Takuan Soho, AFAICT).
Anyway...
After reading Ron Edwards's Sorcerer (the annotated edition), I noticed that he's saying the campaign when he was "just playing the NPCs, and this generated the narrative" as one of his most successful ones).
I'm doing the exact same thing "the father on Narrativism" recommends - although I consider myself a Simulationist. Then again, I've heard the same advice from mainly Gamist players.
Yeah, the divisions in the RPG hobby are mostly BS, indeed.
I had discovered the "just play the NPCs" GMing approach in, more or less, the same fashion as Ron Edwards. I was running a game; the game was set up with interesting characters from both sides of the screen. There were conflicts and alliances between them to give a pause to any Vampire chronicle.
So I just asked myself "why the hell should I prepare it in advance, if the players aren't going to do what I expect anyway - and I find it fun to catch this kind of surprise shots and return them?"
The answer was "no fucking reason in Hell", and so I ran the next session... two hours after the one that had just finished.
At the end, I had more material than I had before, because no PC ran from conflicts. The players laughed, and cried - for real, not roleplaying - and were exhilarated.
Years later, I almost got a beating when I announced ending the campaign...
But all of this was because the players knew that risking your character is fun. To the PCs, that's no doubt the analogue of playing extreme sports...but then most PCs should be extreme sports enthusiasts.

The end conclusion is, to me: You need to teach unfettered roleplaying to the players, if it doesn't come naturally to them. After that, you can be the Unfettered GM.

Most books teach you to be the Fettered GM. Take an adventure, self-made or not. Start the PCs so and so, says the adventure. X happens... After that, Y happens. After that, Z happens (and hopefully, that means you get to meet Zorro). That's how I began running games, too.
But right now, I only need a setting book and easily applicable rules. Everything else, including genre supplements? Yeah, nice, but largely unnecessary. "Just play the NPCs", and if it needed to be said, make them interesting. (Nobody is completely uninteresting in real life, either. If you didn't learn that in English classes, learn it now, and practice. Talk with a boring guy and find something that makes him non-boring).
I mean, the guy that makes your accounts might be a Combat Sambo champion (yes, I know such a guy!) The plumber next door might be an ex-convict, or just having had an interesting youth. You** probably have a hobby that's out of the ordinary for your profession - namely, roleplaying. And you're reading RPG-related blogs! In your FREE time! Seriously, do you have any idea how obscure that is to everyone else? (I guess you have an idea, indeed).
Yeah. People with no unexpected interests and skills are so rare, this makes them interesting. So, yes, it's impossible by definition to be boring.
Don't be afraid your sessions would be boring - just make them interesting.
You don't need pre-planned adventures for that. You just need to have the GMing tools internalised, too. And that means "playing the NPCs as logically as you'd play a PC".
And if your playing PCs is lacking, you should work on that.

Or maybe I should just write a module the way I imagine it should be done.

*Yes, that's for the kind of first-hand experience that I haven't asked for.
**The "you" that's reading an RPG-related blog.