It's only more secure between two parties that can reliably confirm their identities with each other out of band. A CA, however badly implemented in practice, is more secure by design because the worst case scenario (a subverted CA) is no different from a self-signed certificate from a client perspective.

In terms of what you're focusing on in this thread (verification of identity) I don't disagree. But a MitM attack on coffee shop wifi is a problem which is exacerbated by self signed certificates.