If the "make a one use rocket bigger so that it can carry a larger payload" hypothesis is correct, then it would stand to reason that the Spruce Goose would be the future of aviation, but I don't see anyone rushing to build another. So far all I've read indicates that a reusable rocket makes for lower cost in the long run. Larger payloads will come as the technology improves, and assuming Elon is correct and the costs of a launch can be reduced by something like 90%, it's almost always possible to split a large load into two or more sections and assemble it in space.