Yep, I’m all for not overly incentivising violent as opposed to peaceful ways to achieve goals. There definitely have been conversations about this before, and there are multiple ways it could be attempted. One interesting suggestion I think was to tie XP to achieving objectives as opposed to what you do along the way, but I don’t think any solution is perfect.
It’s hard to comment on the balance in the game as it stands as I have done playthroughs minimising death (though not at the expense of forgoing quests) and still not had any problem hitting the XP cap or felt that my character is under-levelled for the content. I’ve not completed a patch 9 playthrough though, and of course the divergence between an XP-maximising approach and one that avoids unnecessary fights will only grow further in the full game if the XP-granting approach doesn’t change. Which is why I think this has come up in the past alongside discussion of level caps.