I think it would be nice if you could make some skill tags ban others, for example, if you choose a skill tag that adds the fire element to a skill, you'd be unable to choose a tag that adds the ice element to a skill.
Viewing post in RPG Maker MV/MZ: Skill Construct comments
And perhaps tags could change the skill name or add prefixes/suffixes to it! For example, a skill named "Blank Slate" could turn into "Fireball" when given a skill tag, and further become "Venom Fireball" when given another skill tag that adds the poison state to it. And maybe it could also add something to the description of the skill!