Also vacuum does not exist. More or less gas molecules exist everywhere, sometimes only a single atom in a $m^3$ or so. Beside that, virtual particles and quantum fields might be also there (more phylosophical question if we could consider these as existing matter).
However, the practical meaning of vacuum is the lack of a practically observable atmosphere. It would be hilarious to call vacuum as, for example, "micro-pressure environment".
On this reason, I believe that "micro-gravity" is not an useful terminology and using it instead "weightlessness" or "gravity-less environment" is no good.
I disagree the killing of the tag.