Well, I'm not a writer, therefore am not speaking as someone who writes in a particular style. And certainly in the three years that I've been around I've seen a lot of "introspection" vs. "non-introspection" debate, and it's obviously been around much longer than I.
Purely as a reader, I would say that there's a place for all styles. There are certainly some readers who dislike introspection of any kind, or others who feel that some stories have way too much. Well, perhaps that's true, but there is definitely an audience for introspection in this particular fandom. I enjoy many different styles of writing, and depending on my mood, I know which authors to go to for a story to satisfy my particular taste at that moment.
For me personally, sometimes I love to wallow in introspection, and I don't feel if there's more than a page it's "too much". If professionally that wouldn't sell, I wouldn't know about that, but I do know that I have read published books that I don't consider nearly as well written as some of the fanfics that I've read, with or without introspection.
Kathy