The RPC interface isn't designed to be used in any scenario which would require SSL, which would be access over the internet or other untrusted networks. It doesn't have the necessary denial of service protections or review to make it safe for use this way, and so letting potentially malicious clients connect to it would be incredibly unwise. If you need to talk to a remote
bitcoind instance you are better off tunneling with
stunnel which will provide a secure, authenticated path without exposing the socket any further than localhost.
As of 2017, support for RPC SSL has been completely removed to support the continued move away from reliance on OpenSSL in the daemon (unfortunately BIP70 mandates its inclusion for the GUI client).