Why add the additional complexity of multiple connection points? Protocols support both of those operations perfectly well and it seems that adding URLs would just confuse things.
Because at some point you will need to deprecate ciphers and when you do you don't want old clients to explode. The domain is the way you version connection requirements so you can support old clients with crappy ssl options without screwing up the security of new clients.
You don't need subdomains or other ports because you encapsulate everything in the protocol. A system that works on a protocol only really needs a data socket which can be simulated pretty easily via any URL with the POSTs working as a bursty stream.
