now basically building aircraft from black aluminum, laying up sheet composites, cutting out parts and riveting them together...
Volume, you need to brush up on how the 787 is made - large, complex one piece composite pieces that are autoclaved then bolted together for final assembly. What you're describing is closer to how the A350 is built - with the advantage of easier reparability but higher weight.
Concours, the designers are quite good at maintaining the desired tip clearances as the turbine heats up - most blade rubs are the result of thermal shocks or flow disruptions (most of the heavy fan rub strip wear we see during flight testing is after very high angle of attack testing where the inlet sometimes separates. Unless there are materials out there that don't change at all with varying temperature, there's not much of a carrot there.