If memory serves, someone once made a simple MAME artwork creator tool that was WYSIWYG... Can't remember who, but third party obviously.

Definitely would be broken these days after the artwork system rewrite, but it would still work for old versions.

Pre-rewrite thoughts on creating such a user-friendly tool exists in https://github.com/mamedev/mame/issues/443

Another broken thing: https://mrdo.mameworld.info/mame_lay.php

Also broken: making MAME bezel artwork with Python: https://medium.com/@ericmulvihill/generating-mame-bezel-layouts-with-python-317f9dda2e6d / https://bitbucket.org/ericmulvihill/mame-bezel-layout-generator/src/master/