Here's one extremely important use-case for #2: router/server admin interfaces. For most people it's out of the question to deal with certificates here, but the advantages of end-to-end encryption are still obvious.

That's just one example, of course. There are countless others.

#3 can't be spun up on an ad-hoc basis. It requires a domain name and a signed certificate. This costs time and/or money, and simply isn't feasible for the smallest websites.

#2 can allow the most simple web server instance created in five minutes to be guarded against passive snooping by governments and hackers.