The exchange hacking did not happen this time because previously quite a number of exchanges had been hacked. Not only exchange with low reputation, but also exchange with high reputation have been victims of hacking and suffered heavy losses. So it is natural for people to suggest “don't use exchanges as a place to store assets” because in reality the risk is hacking and losing asset. It is good that an exchange is willing to take responsibility for its weak security system, but remember that not all exchanges can do this unless the exchange has sufficient reserve fund.

So consider keeping it in a personal wallet. One more thing, entrusting your asset to be held on an exchange mean that you are willing to take this risk.