I'm not intimately familiar with The Witcher story in general (at least beyond 3, as that's the only one I've played and I've never read the books).
But I do think there's a lot of truth to the idea of a story having a beginning, middle, and end - where there's simply no value in continually pulling the characters and lore in multiple directions to bleed them dry.
Of course, there are exceptions where it makes sense to dig into other aspects of the story that could be explored effectively in a video game context. But I'd say that's often the exception rather than the rule.
I strongly suspect that once the next-gen updates for The Witcher 3 arrives, I'll be playing through the entire thing again. As it is, I never finished Blood & Wine, despite it being absolutely wonderful. So I'm looking for an excuse to jump back in.