Actually, many aircraft were assembled in just that manner. The F-86 Sabre comes to mind.
Often aircraft were built in a modular fashion to spread the construction out among several contractors. This accomplished a couple three things:
All the eggs weren't in one basket, so to speak, keeping destruction of one factory from stopping production;
Production increased by allowing a work force to concentrate on one module rather than a complete plane;
Replacement of seriously damaged areas was simplified greatly, allowing a plne faster return to service.
Additionally, lack of some resources required certain areas of the plane to be made of other materials and it was simpler to collect those materials locally instead of long distance shipping.
I imagine the UPS and FeEx fees were exhorbitant.
