1)
The network as a whole should be very resistant to attack, since if one exchange goes down the rest of the network picks up the slack. The concept is similar to how the Internet itself works.
Internet is cetralized system, knock out some DNS servers and it will shatter into small pieces
2)
our dependence on centrally managed bitcoin exchanges
Nobody is forcing ppl to use only that one particular exchange. You are always free to use different. If all exchanges will make a hidden treaty, then someon e will setup a new one, caus it will be profitable <--> open market
3)
bitcoin exchanges for price discovery
Exchanges don't set price but merely reflect the price based on demand/supply.
However, I like the idea of decentralized bitcoin regulator ; )
Though, BitCoin hack-proofness is based on the fact that it is much more profitable for hacker to just mine some more BTCs.
Maybe you have in mind some kind of "natural" resistances as well?
p.s.
plz feel free to correct me if I'm wrong somewhere