What could and should occur would be more security and audit solutions specific to exchanges. But the main thing is that if well guarded, you will hardly lose your cryptocurrencies.
Japan is probably one of the very few countries that actually does that what you are talking about, but it's not enough to prevent thefts in form of hacks.
Exchanges will always have to deal with hot wallets, and hackers are out to breach their systems in order to withdaw as much value as possible, and have it confirm as quick as possible, which is why they mostly go for altcoins. Bitcoin's "slower" confirmations offer exchanges quickly noticing theft the ability to double spend in an attempt to reduce financial damage.
And yes, even if there is a successful theft, exchanges will likely refund you one way or another, but the refund process will always favor the exchange and not you. Let's say you have 10BTC in your account at today's $6500 value, and the price shoots up to $15,000 not long after, they will obviously only refund you $6500 per coin. In case the value drops to $3000 for example, the exchange will suddenly refund you your coins instead of fiat.