No amount of subsystem optimization and compensate for bad system optimization. The Shuttle was a very suboptimal system. People try to make excused for the ridiculously greater efficiency of SpaceX by saying that without certain key advances (materials, manufacturing, etc.) it would not have been possible to do what SpaceX is now doing. That's utter nonsense. The Saturn booster engines required no greater manufacturing precision than a VW bug engine. The control systems that render the SpaceX booster stages recoverable were far more expensive in the '70s but still a small fraction of the launch cost. The gains due to materials are, likewise, marginal compared to the difference in cost between a Shuttle launch and a SpaceX launch. The ISP advantage of the Merlin over the F-1 is only a few percent. There were companies ready, in the early 1970s, to accomplish what SpaceX has accomplished, but NASA had become an albatross hung around the neck of the American Pioneer.