It just seems to me, when one VN has a word count that is larger than entire Science Fictions series, it worries me. It may be great, and there is likely a whole lot of good stuff in it, because people love it. I looked it up, and I guess the 1.8 million is for both games together or something? So it might not be that bad.
I think the bigger issue is that a story of this length is still following a basic plot structure of introduction, rising action, climax, falling action, and resolution, but is doing so across a length that the story doesn't actually support. As I was saying, in 1 million words, the entire harry potter series, has seven different climaxes, FSN has like 3. And as for over written, a whole lot of the sequences at home could easily be cut in half, and the world building, while EXCELLENT, is also often redundant. Shiro's thoughts are often redundant as hell as well. Some of my favorite books needed a knife taken to them. A Dance with Dragons is a masterpiece of actual writing, but about 10 - 15 chapters could have been cut and/or condensed and the book would have been stronger for it. Many times long books are honestly indulgent, and the larger versions are often worse. Interview with a Vampire is a prime example of this.