Zelda doesn't necessarily have to stay 'in the dark ages', in my opinion, but I would hate for too much technology to be introduced.
I agree with Midna666 in that Spirit Tracks walks a fine line- whilst I do not mind some technology in the games--Majora's Mask had what appeared to be artificial lighting in some parts--I really do not wish to see more advanced self-propelled vehicles and other such technology. Still, I wouldn't mind more minor things like the pictograph and apparent lighting-fixtures, so long as they do not become to frequent. I still feel the camera is sort of pushing it, though. It is when these things are not well integrated and seem to stand out that I dislike them.
I've always liked the sort of 'fantasy', even timeless feel of Zelda, and I feel a bit too much technological advancement would poison that.