There are certain "rules" of photography... Several of which I no longer follow.
One of these has to do with noise. Ideally, photographs do not have noticeable grain. I have found, though, that increasing the noise in my photos often gives them more interest and softness. It also allows me to be creative with my post-processing, lending my pictures more of an artsy feel, I believe.
These photos may not be stock quality or be desirable for some publications. The noise is also more obvious the larger the prints are. However, from the moment I turn on my camera to when I finish editing, the creative process is mine and the finished photo speaks to the way I feel about the subject.
Besides, who says I have to follow the rules?