And since many people don't know how to use the keys (since steemit is not at all clear about that) this makes things even worse.

people are forced to use the master key far to often since well... it is often the only key that works. and so people don't even bother to use the correct key.

I heave read many guides on how to use the keys and it is still not clear to me.
Not that the guides are bad, but the way the key system is build.

Since all the money is just protected by one key the risk is extremely high when most people use that key ALL OF THE TIME.

So it is just a problem waiting to happen.