It seems that the consensus is (without actually saying or agreeing on this) that any technique that better communicates the message of the moment is good. The point has been made a couple times about blur that at times it may be a more realistic representation. Could something similar be said about grain?
Now the original post's reaction was probably not to photos where the grain and blur flawlessly combined to communicate the moment. What about photos where large grain & blur are merely for stylized purposed and not adding anything? I guess that would just be bad art, bad, not because of grain & blur in the picture but because of poor composition and communication.