Absolutely a knife should cut. It is its primary function so it absolutely should do that.
A Pen should write. A lighter should create fire. A flashlight should generate a beam of light.
I hold no animus towards the OP or anyone else here (thats ridiculous, this is an anonymous internet forum) but I think the point is you have a few options available to you when you buy a knife that doesn't cut, a pen that doesn't write, a lighter that doesn't spark fire, or a flashlight that wont turn on. You can sharpen a knife, you can buy ink for a pen, you can buy fuel for a lighter, and you can get a battery for your flashlight.
Yes, of course a pen should come with ink. Yes, of course a flashlight should come with a battery. Yes, a lighter should come with fuel. And finally a knife should come with an edge that cuts. Especially if each of these were advertised this way (ready to write, cut, light, etc right out of the box).
Though because we know the right way things should be done doesn't mean that things don't go wrong in the manufacturing process. When that happens and a customer is not happy about their product they could do some of the above remedies (Sharpen, fill with ink/fuel, get a battery, etc) or contact the manufacturer/retailer to get their money back or a functional product.
I think most of the ire here is just people suggesting that the OP do one of those things. Then if the retailer or SOG tells him/her to go get lost, he/she would have a much better case for how frustrated or angry they are.