I pay them to access the internet, every further information they gather about my internet activity does not mean any benefit for me.
If it was easy, it would have been done during the TLS 1.3 process, but after a lot of discussion we're down to basically "Here is what people expect 'SNI encryption' would do for them, here's why all the obvious stuff can't achieve that, and here are some ugly, slow things that could work, now what?"
Edit: in SSH2 the server authentication happens in the first cryptographic message from server (for the obvious efficiency reasons), and thus for doing SNI-style certificate selection there would have to be some plaintext server-ID in first clients message, but the security of the protocol does not require that as long as the in-tunnel authentication is mutual (it is for things like kerberos).
You are correct that you can do this if you spend one round trip first to set up the channel, and both the proposals for how we might encrypt SNI in that Draft do pay a round trip. Which is why I said they're slow and ugly. And as you noticed, SSH2 and rdesktop do not, in fact, spend an extra round trip to buy this capability they just go without.
Aside it's strange https everywhere has been pushed aggressively by many here under the bogeyman of ISP adware and spying while completely ignoring the much larger adware and privacy threats posed by the stalking of Google, Facebook and others. It is disingenuous and insincere.
Only a handful of small specialist firms actually just move bits in the UK. Every single UK ISP big enough to advertise on television is signed up to filter traffic and block things for being "illegal" or maybe if Hollywood doesn't like them, or if they have "naughty" words mentioned, or just because somebody slipped. If you're thinking "Not mine" and it runs TV adverts then, oops, nope, you're wrong about that and have had your Internet censored without realising it. I wonder how ISPs got their bad reputation...