The problem is that people do not want to use the encryption. And they also do not need to share passwords, encryption keys and banking info. In the market you can sale only if you have customers.
A sender does not want to use encryption if it puts an out-of-proportion burden on the recipient to learn how to decrypt. I tried to make Crosspass easy on the recipient. It's on the App Store and Play Store, it's free, and as soon as the app opens the user is asked to type the access code to receive a shared note.
There are already services for sharing passwords and text notes. Most of them are web-based and therefore insecure. But the fact that they exist, shows that there is demand.
privenote.com
onetimesecret.com
Found these guys recently: sharepass.com
If you can send a password, you can send anything, because you can Zip files with AES encryption using 7-zip. No special software is needed on the receiving end to unzip.