Distributed exchanges are the way to go. Every exchange is under constant attack on a daily basis. We need a decentralized exchange for crypto, that is the only way.
Decentralized exchanges aren't the holy grail that people make them out to be. Yes, they can be good for occasional trades (LocalBitcoins style), but as soon as you up the frequency of the trades, the speed at which a decentralized exchange can operate becomes a limiting factor.
Forex-style exchanges such as Bitstamp, BTC-e, Kraken, etc... are necessary to provide sufficient liquidity in the market. Decentralizing this style of exchange is practically impossible.
It becomes a matter of "secure, fast, decentralized. Pick two". You can have secure & fast, which would be a properly operated traditional exchange. Still, there is a single point of failure. You can have secure & decentralized, which is the decentralized exchange that most people talk about when they discuss this subject. It's just not fast enough for many traders though. Then you can have fast & decentralized, but that involves accepting zero-conf transactions and using instant fiat-transfer methods such as Paypal, which is definitely not secure.