The pgfplotstables tag should be called pgfplotstable, since that's the name of the package. Could it be renamed?
That's a good suggestion. I renamed the tag to pgfplotstable. I did not keep pgfplotstables as synonym, because the name is very similar and before a user has finished typing the name I assume he would have noticed the automatic tag completion, so pgfplotstables would hopefully no reappear.