I'm curious what the rationale is behind requiring twenty answers for a given tag before awarding a bronze badge for that tag. This seems to motivate the wrong behavior; in particular, right now I have 100+ upvotes in "interview questions" with only ten answers, and so the best way for me to get a tag badge in that category now is to go around to old questions with that tag and offering answers even if they don't say anything new. I'm not going to do this because I have integrity :-), but I could easily see this motivating people with a few really good answers going around offering a slew of bad ones to get recognition for the work they've already done.
Is there a rationale I'm missing? Or is this a valid concern?