I'm having a little bit of trouble understanding why the HTTPS protocol includes the host name in plain text. I have read that the host name and IP addresses of an HTTPS packet are not encrypted.

Why the host name cannot be encrypted? Can't we just leave the destination IP in plain text (so the packet is routable), then when the packet arrives at the destination server, the packet is decrypted and the host/index identified from the header?

Maybe the problem is that there can be different certs for one particular destination IPs (different certs for different subdomains?), so the destination server cannot decrypt the packet until it arrives at the correct host within that server. Does this make ANY sense, or am I way off?