There's lot of normalmap creators out there already. Free, paid and even online ones, and never had any problem making them for 2d images. So I really don't get what's the point of making yet another soft that works exactly the same as others currently available.
And also, don't forget that current normalmap shaders available in C2, official one, and one made by some other guy (which actually makes normalmaps on the fly without a need of additional objects) are still limited to only one light source. Which makes things complicated if you want to do some fancy effects.