Hardly a centralized system 
But you can see how it could become centralised if development is centralised and you start trying to tell people what code they can and can't run. Telling people what code they can and can't run is authoritarian. There is literally no denying that. Either trust the open market, or stop pretending you're a libertarian.
while you also have the expertise of the oligarchs who hold the majority of bitcoins steering it in the right direction.
The number of coins someone holds does not correlate to the amount of "expertise" they can demonstrate. I don't care if they hold 1 coin or 1 million. If they can't demonstrate the simple understanding that anyone is free to modify and run the code they want, they have no expertise and invested poorly. And again, they should stop pretending they're a libertarian.