I like grain in black and white night pictures, but only when it has a reason to be there (i.e. when you're shooting street pictures and need to use a small apperture like 7.1 or 8; or when you want to capture fast moving objects; or even both at the same time).
Black and white basically makes colour degradation and grain less obvious and ugly, and that allows you to get a shot at 1/160, f/8, iso 12800.
It's just like blurry objects in some of the low light shots, a side effect that in my opinion gives an authenticity hale to the picture. It's about getting the shot, so you do the besg out of what you have: should you need good colours and clean pictures, you sacrifice depth of field and or faster shutter speeds; should you need large dof and a fast shutter speed, you pump up the iso and sacrifice good colours and noise-free images.
Or just go full /p/ and buy a 4000$ body that can do 137816638192763 iso without losing quality.
