Hmmm. I am kind of in the middle when it comes to rude villagers. I wouldn't mind cranky and snooty villagers acting slightly rude to you when your friendship level with them is at the baseline (neutral/starting point). However, I don't think it should be anything too over-the-top when you haven't even provoked them. This especially shouldn't be the case for high friendships.
I do like the idea of a negative friendship system. If you push villagers around, give them trash, hit them with your net, etc. repeatedly, then your friendship level will extend below the baseline, causing your friendship to go into the negative. I like to think of it like The Sims franchise. There was a friendship bar with two sides: If you were nice to other sims, the right part of the meter would fill up with green. But if you were rude to other sims, the left side would fill up with red.
I know WW and CF did this slightly. If you were nice to villagers, they would bow or wave back when you waved at them. If you were MEAN to them, they would shiver or scowl at you when you tried to wave at them. And in CF, the villagers would talk negatively about you to other player characters. I want to see stuff like THIS again, but with way more indications, such as dialogue that is exclusive to negative friendships. If players want more intense rudeness (that is still within reason for a family-friendly game, OFC), they would have to earn it by being mean first.
I would love some sort of friendship tracker - like The Sims games have - in future Animal Crossing games (but more in-depth and nuanced), where we can check how good (or bad) our friendship with each villager is.
I have said this before, but I love the idea of certain dialogue, letter replies, etc. being dependent on friendship levels (whether positive, neutral, or negative).
With that being said, I think a lot of players don't necessarily want villagers to be rude. They just want them to be more realistic. In New Horizons, they hardly show any emotion and their dialogue is a bit bland. I love how older games have conversations that would leave villagers feeling sad, angry, or hell--happy. Sometimes, it wouldn't even be a choice in a conversation. They would just think of something that made them feel a certain emotion.