Oh yeah, I really wish I had played on a higher difficulty for this reason. Especially because one of the most immersive and thematically cool parts of the game for me was the main story section near the end of act 1 where you have to make a blade oil to fight a >!werewolf!< . (Vague wording to minimise spoilers in my main comment.) I really liked this because it made me reflect on what it means to be a Witcher — how the knowledge might be more important than the mutations and the magic.

An additional point to the prepping is that being open-world means that you can potentially go to areas or take on challenges far beyond the "intended" level. On lower difficulties, I didn't feel sufficiently punished for being audacious in that way, and I think the potential for punishment is part of the fun of the audacity. Especially when getting destroyed like this isn't the game "fuck you for even trying", but rather a "try exploring some more, find some new recipes and come back later (or just read the bestiary and find out that you already have the item you need)"