This bug was already closed 'opinion' once by the developers but has been reopened by the submitter.  The developers asked that discussion about this decision be taken to the mailing list.

A release cycle and change later, this continues to come up in discussions, but the submitter of this bug has not participated on the mailing list thread to offer any arguments; so the Server Team has asked me to comment.

I have also posted my comment to the mailing list at https://lists.ubuntu.com/archives/ubuntu-devel/2022-June/042115.html but am copying it here for the record.

The ubuntu-minimal metapackage defines the minimal experience that we consider to be "Ubuntu".  It is possible to remove this metapackage from the system, from a packaging system / policy perspective this is permitted. However, by doing so, you are making the system "not Ubuntu" and you will not receive support for such a system from the Ubuntu community.

We have always taken an opinionated view on what defines the minimal "Ubuntu".  For instance: at one point in the past, upstart was our supported init system, but there were other init system packages in the archive.  It was possible to install these - but only by removing the ubuntu-minimal package.  Requests to relax the dependency in order to allow other init
systems as an alternative were rejected, because that was not the defined Ubuntu experience.

We should always be willing to reconsider the contents of our minimal install based on technical considerations.  To date, however, the objections I've seen to ubuntu-advantage-tools being a required minimal package have not been technical, but rather questions of taste: specifically, some people appear to find it distasteful that a paid service from Canonical is being
advertised without the ability to opt out.

Firstly, users are always entitled to their opinion when it comes to questions of taste; but the Ubuntu developers are not obligated to accomodate differences of taste when it comes to the Ubuntu experience.

But secondly, as I've commented before, the purpose of ubuntu-advantage-tools inclusion in ubuntu-minimal isn't to advertise
commercial services; it's to ensure users are informed regarding the security status of their systems, and to provide a clean user experience for enabling the ESM service - which in some contexts is a paid service, in some contexts not - to provide the best possible security for those systems.

There are two other issues that have come up in discussion around ubuntu-advantage-tools.  Neither requires making the package removable in order to address, and ensuring they are addressed in the package itself improves the Ubuntu experience for all users, not just those that choose to remove this package.

 - https://bugs.launchpad.net/bugs/1956115 objects about not being able to opt out of the MOTD messages.  This bug report however is marked incomplete, as the behavior described does not appear to correspond to the default behavior in Ubuntu Desktop or Server.  If there are problems being unable to opt out, we certainly want to address those.

 - ubuntu-advantage-tools is now a bit larger than it was originally, weighing in at around 2.8MB.  We should always be mindful of managing the size of a minimal Ubuntu install; however I have not actually seen anyone say that they were trying to remove ubuntu-advantage-tools from their system because of the disk space used.  In any case, the team is looking at bringing the size of this package back down to under 1MB.

In conclusion, in the absence of any other arguments being advanced, ubuntu-advantage-tools will remain a dependency of ubuntu-minimal at this time.  This is always subject to revision in light of new technical arguments that might be put forward, but explains the current state of affairs for the released Ubuntu 22.04 LTS.