I actually don't understand why anyone would need to do that in the first place though. If you already have a decent enough sense of form and perspective, and can draw well enough to make a 3D model trace not look like shit, wouldn't it be faster to just bang out a "mannequin" and draw over that instead of having to painstakingly pose shit in a 3D modeling program and then trace over it? Not to mention that you're filtering your idea through two entirely different processes, and you have to be at least somewhat competent at both for it to work with any degree of success. If you're shit at drawing, or shit at posing a 3D model naturally (and if you're shit at the former you're most likely going to be shit at the latter, for that matter) your end product is going to be awkward and bad.
I just don't get the point of using something like designdoll at all.