My two cents on the subject go along these lines:

With sci-fi that relates to anything near-Earth or near-present-reality, there are already solid handholds for the reader to grasp. If you’re going to vary from historical events, physics as we understand it today, or “facts of the universe” then you have the very difficult task of prying the reader’s grasp of their reality loose before you can shift their grip to your facts and reality. This is the barrier most sci-fi authors have to overcome. However, writing a compelling story with fascinating characters will lubricate the handhold the reader has on their reality and allow you to more easily shift their perceptions around. Do it well enough, and they won’t even notice.

With fantasy, it’s much easier to shift that “reality grip” because you get to make things up as you go and the reader, typically, is reaching for the handles you provide. However, once you set up some rules for the characters/world/environment/magic/whatever to follow, you better damn well NOT break those rules or suffer the most vile of revolts from your readers. Even if you have a “good reason” for breaking your own rules, it won’t go well for you.

Another great episode! Thanks to Patrick for putting this one together and for everyone that participated.

You’re so very right that the fire-and-forget (literally) spellcasting concept came from Jack Vance. I had played (A)D&D for decades before I heard the phrase “Vancian Magic” from a friend. I immediately looked it up and started my search for some of Vance’s works. I have a few here sitting on the shelves, but I’ve not had time to delve into them.

I dunno if I’d even try that with a novel these days I was going to publish the traditional route. That seems like inviting heartbreak.

And a totally nerdy note: the for-narrative/play purpose limited-magic systems discussed go back before D&D. Those came from Jack Vance’s books, so were literary devices before being incorporated as a basic mechanic for RPGs.