dnna: I don't really care for the character level, but what if they add an expansion that takes place after Act 3? It would probably piss some people off, since many players farm Nekkers in Act 1 to reach a high level early (I don't see the point, but hey).
I meant this in another way: In a singleplayer game it's not so much about the level, how your character is built (abilities, training etc.) or how strong you are...but about the story.
I know that there are people who play these games like MMOs, trying to get the "best built with the highest dmg/second" and whatnot. You can see videos on youtube where one guy beats the final boss of the game with two blows.
I don't say it's bad. I'm tolerant enough to say that everyone should play how he or she wants to. Everyone is free to explore the possibilies of a game to his or her liking.
What I say is that's it's not important and that developers of story driven rpgs shouldn't base their game design on those players. For a game like The Witcher 2 there is one rule: Story --> Gameplay. If gameplay ruins the story then the game doesn't work. Of course it's also the other way around so the best possible solution is when gameplay and story are in a harmonic relation. ;)
There are other examples, where gameplay alters the story and ultimate balance is unachieveable, or, if tried, would ruin the game. Look at Deus Ex Human Revolution. Or Mass Effect. In the former, different specialisations make the game more or less difficult. If you choose to play the sneaky way, building your character to be stealthy, but encounter an unavoidable boss fight later in the game, where you have to be strong, it will be considerably more difficult than for the player who's all guns and explosives. And in Mass Effect it is part of the game design that some player character classes play more difficult than others. On the other hand they may be more interesting, more demanding and therefore more fun to play.
The only "bad design" in these cases would be if the game is not able to communicate those differences. The human player has to know - not in detail, just in general - that a different play style, a different character class or different ingame gear will make the game easier or more difficult, so that he or she is able to choose.