SpaceShipOne was designed around winning the X-Prize and it was never meant to go beyond a simple suborbital flight that just barely reaches the edge of space.

SpaceShipOne was designed around winning the X-Prize and it was never meant to go beyond a simple suborbital flight that just barely reaches the edge of space. It's a capable spacecraft for that specific mission but the design is quite limited. It requires a carrier aircraft and it also utilizes a very complicated descent mechanism (flairing wings rather than parachutes). SpaceX started with orbital launch capability and then designed a manned vehicle afterwards. This was the critical difference.