The site has gone to great lengths in recent months to stamp out the former -- even going so far as to announce "We're not a store," and to impose a lot of restrictions on project listings.
IMO, these moves have only exacerbated the problem at hand. Now you've got a presumptive majority of users who still treat Kickstarter like a preordering site, but who get even fewer details about what they think they're preodering. Case in point: lots of blog posts like this one, which claim they grok the idea that they're not preordering finished goods, but nevertheless complain that they're not preordering finished goods. There's a very clear disconnect between intellectual admission ("I realize I may not actually get this item") and emotional expectation ("Where the f--- is my item???"). This is a recipe for cognitive dissonance, and it leaves a lot of very vocal users frustrated. Some of those users may be right, and others may be off base -- but they are Kickstarter's problem, regardless.
Quite frankly, I don't think there's a fantastic solution to this problem. But project categorization/tiering seems like at least a halfway decent step. Kickstarter should ask its listers to choose which stage of the idea they're in: early concept, prototype, pre-sale, etc. (I'm sure they can come up with better names for these categories). And that stage would be made very clear to the users/backers from the get go.
I don't think Kickstarter can continue to grow, or even last, without preordering. That just seems to be the dominant use case most people have for the site. It's here to stay. If Kickstarter shies away from it, some other crowdfunding company will claim the space and leave Kickstarter in the dust. Rather than trying to stamp it out, Kickstarter should embrace it -- but at the same time, take steps to differentiate it from true kickstarting.