I agree 3D printing is primarily used for rapid prototyping, and it's well suited for that purpose. However I'm very confident it'll make its way into mass production as the economy of scale catches up to the technology.

You can not 3d print a custom fabricated carbon fiber thigh sleeve (for lack of a better term)

Not yet but we're getting there. Several companies have prototypes for carbon printing and I imagine in the next 5 years carbon fiber printing will be feasible for low production number parts.

and armature with spring tensioned steel shock absorption with titanium connecting hardware.

Steel and titanium can both be printed, though you would need to treat the steel if it was a spring and printing hardware you can order from McMasterCarr is a bit silly.

To continue the analogy - nothing on a Ducati is a 3D printed piece. Perhaps the prototype objects were 3D printed. But the final objects are invariably produced with much more refined processes (forged, injection moulded, cast, etc.).

3D printing isn't used on mass production because it isn't yet cost effective, apart from that it's entirely feasible. There's nothing about 3D printing that's unrefined, Boeing prints titanium pieces for their aircraft. 3D printing allows for a much greater freedom of design since you're not beholden to the capabilities of your CNC equipment and tooling budget. Koenigsegg, for example, designed turbos for the One:1 that were too complex to cast reliably. Since it's a low volume production they were able to justify the increased cost of printing the turbos from stainless steel. They also 3D print a number of HVAC components for their cars.