The Chinese are already doing things like this, although not the same exact implementation. It is a nice concept if not a bit spendy, by my calculations $60 for the mount, another $15 for the GoPro section, if you want something other than all black it adds another $5. Compare the K-Edge combo mounts at $65 - $70 dependijng on size. Individuals like myself and other 3D model designers here that use a printing service (ponoko, shapeways, imaterialize, etc) generally do not have the ability to add hardware to the designs without diverting all orders to their own location to include it. The metal spacers used on the stem bolts are a critical part, that typically cannot be done by the print service.

I love the concept, might even consider buying one for myself if it were cheaper.