I chose other because from what I've read on this forum, it's all of the above for the most part. It's just so radically different from any other game in the series that it doesn't feel like a CV game. That is the real reason. Many people agree that if it was a stand alone series separate from CV, it would have been received a lot better and wouldn't be hated so much. However, because it is called Castlevania and is so different, it seems to be considered blasphemy by many CV fans. And, to a certain extent, I understand where they are coming from. I, too, don't really consider it a CV regardless of its title.
On the other hand, instead of being hated so much, we could always say that LoS takes place in an alternate universe. That was IGA's explanation for where CotM, Cv64, and LoD fit in on the time line. They don't because they take place in an alternate universe. It may be a bit of a cop out, but it could also fill some plot holes.