Silent Hill went wonky between Silent Hill 3 and Shattered Memories, but I'd say thats down to Team Silent leaving and Team Silence arriving (hell they've only just got a permanent writer in).
That's true about Resi, I think Team Silence have been too afraid to try and take Silent Hill in new directions (up until SHSM) because of the whiny fanboys, but with SHSM, I have a feeling they just thought "**** it, lets get rid of all the series staples that are ruining the series" [The Order/Samey looking otherworlds/The 'I forgot I did that!' storylines], Team Silence have already said they're not going to try and emulate Silent Hill 2 and it's twist - also it's not Murphy's story, it's the story of the town and everyone that's ended up in it - it's not just Murphy who is visiting his personal hell
Book of Memories is an example of Silent Hill starting to experiment a bit more - A Silent Hill game with multiplayer and confirmed DLC?