There are shapes that can't easily be generated with traditional manufacturing processes. For instance, with 3d printing you can make a fully assembled crescent wrench. Traditional methods require you to make 3 parts and put them together.
I can't say what it will be useful for, but it opens up a lot of new design shapes. It'd be pretty shocking if that didn't result in anything useful.
Ohh, I agree that there's plenty of uses. You have to look no further than the Lexus LFA's chassis to see what 3d "printing"(woven in this case) technology can do.
It's just that 3d printers aren't going to revolutionize manufacturing or whatever it is that armchair pundits say about them. They have a place, but it's not sitting next to your microwave in your kitchen where you can download wrenches off the internet and print them into existence(and have them be at all useful). They are useful for hobbyist projects, for rapid prototyping, and for highly specialized work where traditional manufacturing isn't feasible(e.g. biomechanics).
I can't say what it will be useful for, but it opens up a lot of new design shapes. It'd be pretty shocking if that didn't result in anything useful.