Ease of use is still a big issue. You can't just buy a $500 printer and use it straight out of the box consistently.. you have to fiddle, tweak, adjust settings, test.. it's a tedious process for even those of us who are very technically minded. You can spend $2k+ on a makerbot and still have the same issues.

The next problem you already touched on.. people don't know how to model stuff. Thingiverse and the like are obviously helping in that regard.. but what happens when somebody who can't build 3d models needs a specific thing for themselves? In your example you mentioned a knife and fork.. what if you want them to match what you have? You still need modeling skills to take full advantage of even the best printers out there.

Kyle