As we are increasing in size and in number of users, we start to see more often users which have enough reputation to create a tag, and without much oversight, they go on a spree to add that to 50+ questions in the span of a day or two.
This is horrible, and Martin Sleziak has already had one good suggestion to limit the ability of the tag creator in editing in the new tag for a cooling period of at least a few days.
And I am not saying that the users doing that are definitely just gaming the system. I am sure that in their minds, they are trying to do a good thing. But the tagging system is fragile, and it requires collaboration and not one person working alone.
Yet, this happens. And interestingly, when it does, it almost always ends up rewarding the user a Taxonomist badge for their efforts. Which hints to me, that this reward-seeking behavior might be an underlying cause of this.
I propose that much like the fact self-edits do not count towards editing-related badges, self-tagging will not count towards a Taxonomist badge.
If nothing else, it will bring those users to meta to ask why they haven't received the badge, and will give the rest of us an opportunity to overview the new tag and its necessity.