insurance companies don't make money by paying their customer when something goes wrong. instead they make money when they don't pay them and because of that they are doing all they can not to pay. in other words eve if an exchange were insured one day, that still wouldn't make it safe and i wouldn't say they "need it" because that wouldn't  change a thing in my opinion, they are still going to get hacked and we won't get our money back or they would still scam us and we still wouldn't get our money back.
in the end the customer (we as traders) are going to lose as long as we are using centralized exchanges whether they are insured or not.