Elon's spoken at length about the choice between design philosophies since the early days of Falcon. I'd submit that trashing Falcon 1 after the first successf

Elon's spoken at length about the choice between design philosophies since the early days of Falcon. I'd submit that trashing Falcon 1 after the first successful flight to build Falcon 9 is an example of exactly that. Part of Falcon's success so early on was due to the choice of intentionally simple systems - a single pintle injector in the Merlin engine, RP1 propellant which is well understood, lots of relatively safe choices. And lots of work with the grasshopper test vehicles. But on flight 1 of Falcon 9 they flew Dragon. Flight 6 used hardware revision 1.1 and was the first to attempt a propulsive return. Flight 9 added landing legs. They made changes to basically every flight until Block 5 with flight 54.