yeah, after the hack etherdelta people do also not trust anymore on decentralized exchanges. But the main reason why most people prefer an exchange is its volume. With more volume they get more profits.
but what happen with etherdelta prove that decentralized exchange are more secure, no one lost money except those who imported their private key on that fake website, if you use metamask and always check the website you will loss nothing. I use etherdelta when got hack and I didn't lost any ether or token, my wallet still safe.
Also if a centralised exchange is hacked then you also lose your documents and other personal details for the hackers who now can sell them to the party paying the most money