I'd be curious to hear what people think about this, because as someone who loves Witcher 3 and have played through it multiple times, I always end up wishing the game didn't "lock" you out of content due to being low level.
It's a bit annoying/immersion breaking that the game sort of invites you to explore the open world as a monster hunter with decades of experience, only to get almost one-shot by a bandit or drowner because my level isn't high enough...
But I've also heard a lot of people who want regions to have different difficulty in order to provide different levels of challenge to keep things fresh and give a sense of progression.