As a content creator I have been using the personal tag in order to make my OC clearly visible and therefore sortable or (in my dreams) followable - you know, feed the horde of fawning followers that I have - as 8bit said, it also allows people to easily hide my OC if they don't like it. I typically have used blog._refugee_ and poetry._refugee_ though once or twice I've messed it up and called my OC something else somehow.
I see a great value in having those tags from the content creator side because then it's all there if someone wants to go look!
However, I happen to know how many people follow poetry._refugee_, and it's like two, and I do suspect that the value I find in the personal tag (for in case! basically) is not equal to the value that Hubski users are actually getting out of it.