It's probably just an issue of the right target market. People like me aren't it, but people who are less concerned about such things may very well be. A zero-knowledge implementation is still a great idea to protect them, even if they don't really appreciate the protection they're getting.
By the way, I realize my comments have been critical, so let me say the other side: good work! I wish you all the success in the world. Building and releasing something is a major accomplishment, and anything you make won't be right for everyone. That's not a fault with your product. That's just the fact that different people have different needs.
I agree the primary appeal (and thus market) of this app is not technical, but of course it's still important that the technical aspects are vetted and secure.