I have seen images which use grain to advantage. That is, the image is enhanced, to me at least, by the presence of visible grain. Then there are some images, some very recent on APUG, which have extremely smooth tonation and in which grain would be a distraction and therefore objectionable to me. Please note. "...to me". In the latest edition of PT there is an article on wedding photography rendering photos having nothing but grain which I find bad at best. Don't know what "they" are coming to.... I cancelled my subscription last year but am still receiving issues. I hope "they" don't expect me to pay for them.
I try to limit grain. I have never consciously attempted to include it. However, most times when it has occurred, I live with it.