Looking at the tags field on a develop feature, it inherits all of the tags from my main roadmaps workspace. This isn't the behaviour I'd expect, I would expect a develop team to have its own unique set of tags of primary relevance to them.
In playing with feature workflows outside of develop, earlier, I solved this by creating a custom feature field called "<subteam> tags", which then allows a separate pool of tags for that specific purpose.
You're right that creating additional custom fields is the best way to solve this currently. I'm marking this ideas as "future consideration" so we can continue collecting feedback.