Reasonable on 05 March 2010
No idea. A linear experience will always be easier to control and often produces better results, particularly for games with a narrative or a story.
Open world can be fun, too, but it brings challenges rarely overcome if you want a narrative, too. Even the big open worlds are really little more than a playground to mess around in until you decide to follow a quest for a while, then the become as ruthlessly linear as anything else.
I guess it depends on what people expect. I mean, I can understand if you want the ability to wander about picking and choosing quests you'd find RPG type games that don't do this to not suit your tastes.
But it's just an option like any, and not inherently bad.
Try to be reasonable... its easier than you think...
