Since when was exchanges stable? Ever since Mt Gox there hasn't been much improvement. There was cryptsy, which was the premier choice for altcoin exchanges back in the days, which in the end blew itself up. There was the bitfinex hack. There was poloniex, which is unstable as hell even now.
The exchanges that you listed aren't even as trusted as these exchanges, first you need to move to bigger and more regulated exchanges to ensure that even in the event of something going wrong, you have the peace of mind of knowing that it's regulated by a government. These small exchanges, cryptopia, coinexchange, novaexchange, etc. can run away any time they want.
Exchanges hold your money for you. Any service which requires you to send them money is risky, and often unstable.
As my particular interest is in staking coins, these exchanges are (in a lot of cases) the only ones available to me.
the option of moving to bigger exchanges is not always applicable.
Luckily, I have only been caught for a few hundred bucks as I withdraw to staking wallet or pool as soon as I exchange.
Perhaps someone with an entrepenuerial attitude can develop an exchange using all the others as a guide
as to what not to do ??
Well, obviously exchanges have to be used. I'm not saying that don't use them at all, that's just unrealistic and dumb. There is still a need for exchanges but these exchanges right now are really very very risky to use.
What I can say is that if you just deposit your coins, exchange, and withdraw straightaway you'll find that the chance of having a problem is much lower than if you stored funds on it full time and used it like a wallet. Exchanges are not wallets. Hacks happen all the time, just like coincheck's NEM hack recently.
Launching an exchange and making it mainstream takes a lot of advertising. Binance has done a great job but they probably paid a hefty price. The new, small exchanges never get the publicity they want.