BCNEX took people by surprise, so many believed in that exchange, I had a friend that had close to 8 ETH stock in that exchange and he tried to contact their support, all to no avail. I also learnt a very important lesson with this, not to hodl more than enough in any exchange wallet
Yes, it is not recommended to store too many assets in an exchange wallet, because everyone who plays in crypto must always have a personal wallet whose keys we can hold in full, BCNEX has provided a very valuable lesson for everyone, so make this as the key to success elsewhere.
Exchange is not for store your tokens or coins. If we talking about new exchange, why will we use new one to store. Actually to store or some time store, we have to store our coins in exchange. I think only a few users left exchange after sell coins. Traders always store coins in exchange so we should use Binance, not like Bcnex new exchange.