So we should concentrate our efforts on an easy-to-use secure communication tool with not so low fees maybe.
I think so. The world is full of messaging tools, but I cannot think of any easily access file where the messages are permanent and verifiable that someone agreed to something or said something, i.e. you can't fake them, delete them, change them, if they are easy to use then people will find uses for such a thing - and this does not need to be cheap.
This is more like contract agreements etc. than simple messaging. For these types of things we don't need to lower fee.