IMHO the easiest step to make the "balance" more enjoyable is simply removing the bonus/malus that depends only on the level difference. I know, there are mods for that. Hard monsters are hard like they should be, not more, and the same for easy monsters (not easier).
If you are good and prepared you can tackle almost anything at any level; if you want it easier return later with better skills and equipment. This should satisfy both who wants an hard challenge any moment and who want such challenge to be hard but not tedious.
After that we can discuss if and how Geralt/equipment should grow, how powerful the enemies should be from the beginning, how they scale among themselves (and not compared to Geralt; I can understand that different Drowners have different strength, but not that it is caused by the player's level). How skills and slots should work/interact (the actual system is pretty awful with both useless and overpowered skills; oils are lame, mutagens are lame). Remember, Geralt is a century old witcher, his power should not grow too much in the few weeks the game take place.
I don't know many games, but I think Dark Souls 2 is a good example to follow. Monsters are static, some weaker and some stronger, but they don't change with the difference of level. There are people that finished it at lvl 1 with starting gear (the almighty mace), because the most important asset is the player's skill and his knowledge, character's stats came later.