The Witcher is very specific about who Geralt is, and even Mass Effect starts from a fairly defined background.

Very good point.
I'm obviously just going on 2nd hand accounts, but because of how different this sequel is to the first game, I can certainly see why fans are disappointed. They did do such a good job at creating a world for so many possibilities in the first game, and to just replace that with a more linear experience, well I'd be pissed too.