There are some things Docker, Inc does that upset me, but I can't say this is one of them

Containers aren't really supposed to be precious. With live-restore enabled the daemon restarts should be transparent

I have a hard time thinking of a situation where I really cared about the runtime version

I prefer automatic updates, especially something like Docker that can be a security liability. Being in the docker group is essentially a path to privilege escalation

It also gives the new stuff more road testing

That's an interesting way to provide a free tier. I think starting a new product this way could go over well.

Please developers, don't let this become a thing.

As a developer, wouldn't I want to know the effort I put into maintaining old versions was being compensated at its fair market value, so I know I'm working on something people care about?

Requiring people to update to the latest version as a condition of providing support is perfectly reasonable.

Giving something to me for free and then altering that free thing at a later time against my wishes is not reasonable IMHO.

Consider an e-book: would it be acceptable to give out free e-books, then change that e-book (remotely) at a later time? What if those changes remove value? Or, what if they introduce content that you find highly objectionable?

Now, imagine a future where every (digital) thing is like that.

Docker can do whatever it pleases in accordance with its licensing, but we don't have to like it.