It should be noted that the meta-package "ubuntu-mate-desktop" *(or any -desktop for that matter) is likely to be missing upgradable packages should you upgrade in the future. Here's a quote from another thread about the subject:
While it's safe to remove, it's usually a good idea to install the meta package again before performing an upgrade, and repeat the process after an upgrade completes. There is a more advanced solution however, here's the thread: