Coinex claims that the hacking was done due to the phishing site.
Hm, I can't find the source of that info so can you maybe share it? All that I could find is Coinex saying that private key of their hot wallet got leaked but they don't explain in detail how exactly that happened.
This hacking shows that even a reputable exchange can be hacked, it is not safe for the users to store their funds in the exchange besides storing their funds in their wallet.
While I do agree that even the most repuatble exchanges can get hacked (and they do) I don't think that Coinex falls into that group. Addiitonal problem is that they are a relatively small exvchange so hack of $70M is not somehing that they can sort out easily and might even endanger the existence of the exchange.