But in the case of KeePass, it’s not a single dev. At least if you plan on using it with your phone. It’s a bunch of independent developers who may or may not really talk to each other. Dominic makes it very clear that all of these mobile apps are unofficial.I hear that, but I see it more as using a particular app as a client to handle an open file format, like using any number of apps to handle markdown, or more comparably, an SQL database. The data isn't locked into the app.
Edit: I see your point about security issues etc. I suppose that's a judgement call as to whether a single dev is to be trusted less or more than a team