If we implemented https with MCWS you'd need a real certificate from a certificate authority and your own domain name for the internet reader in MC to be able to connect to the MC server without doing some futzing around with the internet security in windows. There are places you can get free ones for personal use for 1 year terms but they don't make it very user friendly from what I've seen so far...
Why? You could just generate a self-signed cert, like every router on the planet uses for its web interface.
I wouldn't think you'd even
offer the option to upload your own cert unless you really, really want to expose that to the end user. A self signed cert is absolutely fine for confidentiality (the encryption works fine) it just doesn't provide
identity without using one signed by a CA.
Identity for MCWS isn't extremely important (you'd notice if you connected to someone else's server, after all), but privacy could be, because with MCWS as it is, if you poke a hole through your router, any malicious actor on the same network as your client could log in and delete your entire Library.
There
is a way to reasonably secure it now (while still allowing JRemote/Gizmo to easily connect without VPN) but it is a huge pain, requiring VMs and other nonsense, and you give up the ability to update play counts on the server with your mobile devices.