Leaving your coins on the hot wallets of any exchange is never considered to be safe.Being a hot wallet,it means that it is connected to internet and it can be easily accessed by the hackers.So that is why it is advised to keep your coins in an offline cold wallet but it totally depends upon you and the amount of coins you are keeping on the exchange. If you are leaving an amount of coins which you can easily afford to lose then I don't think it should bother you that whether it is safe or not.You can simply stake them and enjoy regular interests.Another point is that if I am trying a new coin and it is quite less in number that I will not make a wallet for it.I will simply keep it on the exchange. So it is totally your take whether you want to keep your coin's in an offline wallet or you are daring enough to take the risk.
Talking about the insurance then I don't think any exchange will take responsibility for such hacks and will reimburse you.