In his latest Patreon update*, one thing Martin says is
I’ve also been refactoring the Ubuntu MATE seeds and meta-packages. The
main end-user advantage to this work is that, for example, Firefox can
be uninstalled without taking the ubuntu-mate-core and
ubuntu-mate-desktop meta-packages with it. This is currently a
work-in-progress and requires that MATE compatibility is added to many
GNOME and Unity packages.
* I think you need to be logged in as a patron to view the whole post.
I just updated my 16.10 virtual machine, and afterwards I ran sudo apt remove shotwell
and sudo apt remove libreoffice*
. In both cases, the ubuntu-mate-desktop
metapackage wasn’t removed!