Considering that most people nowadays often find it hard to store and protect their cryptocurrencies, it's best to delegate the responsibility to a middleman. A bank of crypto would fit the bill nicely, as people would be able to secure their cryptocurrencies without ever having to follow the necessary precautions to prevent hacks or theft. Nonetheless, do you think that a Bank of Crypto will happen anytime soon? If so, why? 
Will a bank of cryptocurrency be appearing soon? I don't think so and the answer to that is because it would be hard to get something like this approved by the government or regulators. And yes, this very idea is defeating the very essence of cryptocurrency. However, if there is really a big demand for this service then there is a big chance that an entrepreneur can take the risks and offer this same service to the targeted market. But I am sure it would not be easy and maybe it may not worthy at the end. The concern here is protecting the digital assets but there are now many ways we can do that without transferring the assets to a middleman which is actually also a risky thing to do...what if the bank can be hacked or if there is an inside job or maybe if it will go bankrupt? Assuming that I have a good hoard of Bitcoin, I prefer to store them in a hardware or cold wallet instead, just making sure that I have the keys with me hidden somewhere safe.