I totally understand why people don't like the villainess trope, and even though I find comfort in the trope, I get tired of it too sometimes lol.
The above comments are really good at talking about the villainess stories done well, but if you're just thinking "How in the world do people enjoy this cliche!?" I'll give my two cents as a person who loves it
I think it's a more complicated version of the "push and pull" trope that basically any rom-com fanatic will know about. Since the villainess usually enters the story as a person who is hated by everyone, she assumes that she's not important to the story and if she just acts nice to everyone then disappears once the OG protag enters the scene, no one will care. But then! Everyone starts chasing after her and pampering her to try and get her to not leave.
Because the villainess in these kinds of stories has basically no expectations for anyone around her, it gets really addicting (albeit frustrating if overdone) to read about the side characters trying to, like, make her happier, or more dependent on them. Also, a little jealousy amongst the love interests doesn't hurt too much
The whole setting is in like a kingdom or an empire, and the male lead in this story is usually a king, emperor or duke. The idea of someone marrying to a person of higher power appeals to a lot of people, like how the "commoner marries CEO" story was (or still is, I'm not sure) popular
The thing that is usually added in these kinds of stories for spice are wars (doctor elise) or controversies with the church or people of similar power (fantasie of a stepmother(?)). Plus it's in a historical setting anyway so that kind of thing is usually expected to be added
I especially love the ones that involve family 'cause they make me cry (fantasie of a stepmother again, harley takes the house, who made me a princess)
To be honest, my taste in writing has diminished greatly since I developed my addiction to reincarnation stories (especially since I read a crap-ton of fan translations and mtl). I was reading merchant of venice and my mind was absolutely blown at how everything in the story tied perfectly together in the climax, and then I started to wonder if that kind of thing is normal and I've just forgotten how a non-fantasy story is written (but then again, it's shakespeare)
Yeah that's how much I can talk about it without cringing at my lack of ability to put my thoughts on the genre into proper words
edit: fixed random sentences