If it fuels the story and makes the game richer for everyone, I’m all for any changes players want to make.If you take a look at my earlier thoughts on the two sides of GMing, I think this idea ties into the Run-Time GMing set of skills, but it absolutely needs the Design-Time setting details to have any chance of working during play.
This dualism in what you need to be a good GM sticks with me. It's very much the Taijitu: The Yin of design encompasses all the passive elements of setting and fills the GM's bag of tricks, while the Yang of running the game and incorporating the players' decisions drives the action through scenes to resolution. It doesn't make sense to have one without the other.
You can find help with Yin in designing game elements and updating rules. You can find help with Yang in guidelines to make your game run more cleanly and to speed up combat. Rarely do you find help with both sides at once, and yet that's the essence of GMing.
Changing gears from Yin to Yang can be hard, but it's natural when you think about it. At the end of a really good game, you immediately start designing what you'll need to support the next game if only mentally. And while you design game elements, a part of your brain toys with how the game will run when you turn it loose on your players. It's completely organic, but it can be very hard to talk about effectively and make sense. The idea that one concept flows into its opposite is a very Taoist approach to GMing.
So what does all this mean? I think these two "opposite" sides of GM skills need each other to strengthen your overall game. Even the awareness of this Tao of GMing can let one side of your GMing experience inform the other, and that will make a better game for you and your players.
If you ask yourself how your design will work in play while you're designing, you embrace the Yang within the Yin and your design will make more sense. If you use design elements that are flexible enough to randomly insert during play, you embrace the Yin within the Yang and make the experience of your world far more rich for your players.
Is this revolutionary? Not really. Great GMs have been doing this by pure instinct for years. But if you're just starting out, I think it will help to know that being a GM takes more than making a great adventure and knowing the rules. If those two sides don't work together, then your game won't be as good as it could be.
And that's the point, ennit? We're all striving to become great GMs making great game experiences.