Think that people are more capable of discerning what’s acceptable in reality and in idealization than what people give them credit for, making the idea that it’s because we know they’re secretly nice as the audience not a catch-all answer
My favorite archetype of characters are attractive girls that are complete sociopaths, I.e. Malty, Mami, Clementine, Seryuu Ubiquitous, etc., who are presented with no redeeming qualities, and I would find them less fun to watch if they tried presenting them as secretly nice
Kindness/meaning well is a likable trait in humans but what’s preferable in real people is not always relevant in what we like to see in fictional characters, and making that conflation is unnuanced
Don’t think overly sadistic tsundere are all that different, it’s possible that people like the overtly tsun elements about them without wanting to get abused in real life, even in a masochistic sense of the word, let alone something more severe
tl;dr stop working under the assumption that likable characters need to be liked for traditionally “good” character traits, that’s just being myopic