I agree that assumptions on the application side are the bigger issue, but it's less about encouraging client/server architecture in general. It's often very helpful, even among peers, to drop into a mode where somebody is wearing the client hat and somebody else is wearing the server hat.

The sin here is the hierarchy imposed by SSL and its infatuation with server names. Its says: these people are lords, they can wear the server hat. As for the peasants, your client hats are over there. If we catch a peasant wearing a server hat, the browsers will make them look like a criminal.

Our applications have evolved accordingly.