>>720533335
Because the series never had an established style or substance to itself.
Silent Hill 1 was literally Konami telling Team Silent "make Resident Evil, but more horror."
Silent Hill 2 was a drastic departure from the original, was lambasted by a large portion of the fanbase at the time, sold half as much, and was a complete plagiarism of a David Lynch movie ("Lost Highway").
Silent Hill 3 was supposed to be an action game, this got changed late into development, the game was stitched together, and sold less than the previous two titles.
Silent Hill 4 was a complete experiment and wasn't even supposed to be a SH game. It also featured radical changes in gameplay and storytelling.
See what I'm getting at? The series never really had the chance to have a "core" of solid, relatively similar titles, like Resident Evil, in order to establish a proper franchise.
