We don't use obvious grain, usually. That's generally precisely to evoke something about the past -- for flashbacks, a period look, etc. A sense of grittiness like 70s movies, etc.
On the other hand, a small amount of constant grain or noise is intentionally often introduced because otherwise images feel too static and end up looking almost fake. Similarly, dithering is intentionally added to audio, like mastering CD's or tracks. It helps prevent artifacts in video and in audio.
On the other hand, a small amount of constant grain or noise is intentionally often introduced because otherwise images feel too static and end up looking almost fake. Similarly, dithering is intentionally added to audio, like mastering CD's or tracks. It helps prevent artifacts in video and in audio.