So the B767 is a 35 year old design! The C-130 is a 56 year old design. The A300 from which the A330 derives is nearly as old as the B767.
Also tanker tasks are not all max range/max payload/max delivery ops. The technical shortfall of capability re the KC-45 is only a technical one on few possible occasions.
Under the current climate if I was a US taxpayer I'd keep the jobs in the USA if I could. Jingoism applies equally around the world...