As we are not using icons provided by the icon theme of the desktop
environment, which in my case should be
https://gitlab.gnome.org/GNOME/adwaita-icon-theme, there is a visual
mismatch that some people might find irritating, but that is nothing new
with Emacs.

>> FWIW I don't think there is any harm in adding the icons anyway.
>> Disregarding visual appeal, I think a slightly less subjective question
>> is would it help attract the attention of new users to useful operations
>> when they are dealing with packages, and I think that the answer here is
>> affirmative.
>
> I'd like to avoid the situation where adding the icons will cause a
> flood of complaints about their appearance.

Understandable, but unless we find some way to detect and use the right
icons on all the systems that Emacs supports, I feel that this is
inevitable.