I find it somewhat interesting, along the lines of the previous comment about expressing control over a subject in as many ways as possible. I do find scenarios where the milk has been modified, either magically or technologically, to have effects on the drinkers (sleepiness, loyalty, truth-telling, hypnotic, etc.) very interesting.
Yup. Or contagious milk that makes women who drink it experience breast growth and lactate prodigiously themselves, and drinking their milk passes the effect along... combined with some mc effects like vastly increased libido and tractability.
One of the other fun things about the kink is that being milked can have implications of being a very submissive act, with implications that the woman is being treated like livestock of some sort. But it can also he a very dominant act, where nursing someone is putting a parent/child spin on the dynamic. So imo it can add a lot of spiciness to a situation.