After several inquiries, Chief Producer of
Resident Evil: Darkside Chronicls, Masachika Kawata issued an official
statement as to why Darkside and
Umbrella Chronicles were rail shooters as opposed to third-person shooters like
Resident Evil 4.
I personally don't care what reasons they give, I'm not going to go spend money on Darkside Chronicles after I've seen what they can do when making third-person shooters. A rail shooter always seems like a downgrade from other games to me, no matter how many special features it has (Star Fox being the exception). Put a survival horror game like Resident Evil on a set path, and I'd say about two thirds of the horror aspect just goes right out the window.
Here's hoping for an original Wii exclusive Resident Evil game.