I have seen recently that, When I re-tag a question, It is considered as edit. Then I can even reverse my vote on that question. I have a feeling that, It should not be considered as edit since, The actual meaning of the question is not changed. Also I think, very few of the answerer get information from tag. (I also answered a question, where OP put only a xubuntu tag to inform me, he is using xubuntu. later I have to edit that answer). Also, someone might misuse this feature for removing their upvotes.
So, my question is, Why re-tagging should be considered as edit?
My view is: You have given the chance to re-vote the question after edit, because in that way, you can re-judge the question and can give your vote accordingly. As, simply re-tagging doesn't change the meaning of the question, why should you be given the chance to re-merit the question?