The problem is that NASA is designed around long term and expensive projects.
At one point, a fast iterating company like space-x will surpass their achievements.
Why would SpaceX bother doing science, though? If you imagine a project like Voyager, you might think they just dump the data and "go home" (not quite, obviously) but to analyse the data and to know what to look for they had to hire geologists and meteorologists (for example) along with the planetary scientists and co.
NASA should be about long term and expensive projects, SpaceX is just a tool to achieve that goal which is to do new science regardless of whether it is in the air or in space.
