I like this change, and I'm supportive of codifying that GMs have leeway to provide the best experience at their table. I also believe that this change will be comforting to new GMs who have a lot of stress about running adventures "wrong" despite being well within the Run as Written guidelines.
I can't think of any critiques to these changes that can't be addressed by "Use Common Sense and figure out what works best for the table".
Since GMs are empowered to make adjustments so they can better run the scenario as intended, it would be nice if the scenarios included more "designer commentary" to make their intentions more clear. I can provide some examples of where this might be helpful, if desired.
All in all, I'm glad to see this change on the horizon!
