On the aesthetic appeal of grain in photographs, it's worth noting that even before digital, photographers were particularly interested in the look of the grain

On the aesthetic appeal of grain in photographs, it's worth noting that even before digital, photographers were particularly interested in the look of the grain. This is most clearly highlighted by the fact that even when film manufacturers produced higher quality film with less visible grain, the older film emulsions were still available as some people preferred that look. For example, Kodak make 'traditional' and 'T-grain' versions of their B&W film (I believe the 'T-grain' style has the grains stacked vertically rather than horizontally, allowing for more light sensitivity but smaller visible grain). So, if you want ISO 400 B&W film, Kodak will sell you TriX for traditional grain, and Tmax for modern 'T-grain'. The article discusses grain visibility in shadows vs mid tone and highlignts, and suggests that grain is visible across the entire image. This isn't true. The process of exposing film converts silver halide to silver granules where the light has been captured, so in shadows, the grain is purely silver halide which is removed by the fix step when developing the film, leaving only the film base. So, unexposed film (shadows) have no grain, highlights have all the grain. This is the opposite of digital, where if anything, noise is most visible in the shadows, whilst on film, shadows are pure black with no noise (from grain). Another thing, different printing processes cause the grain to be more or less visible. Traditional enlargers use collimated light which produces very sharp images, but accentuates dust and film grain. This fell out of favour to be replaced with diffuse light, which drops the sharpness a little, but is much more forgiving.