"With few exceptions, not only is the space in Mailbag wasted, but thoughtful readers who would like to submit an occasional comment are excluded." I think this boils down to, "You publish too many opinions with which I disagree." As to those who submit mailbag contributions that are not published, there is the chance, based on the standard of writing I see elsewhere, including the R-G, that the submissions are so poorly written as to be unpublishable no matter the opinion and the issue.