I think you're taking other people's tastes and what they enjoy too seriously. If some teenage girl is giddy over Astarion, a fictional vampire, it has nothing to do with you. Also, these characters were meant to appeal to the general population, so Larian was obviously successful that way. While I do think Astarion and Shadowheart are a little overrated because they are the most conventionally attractive characters, I don't think the people who love them are morally "wrong."
Also, a lot of people who are playing BG3 probably are teenagers, and so what? It's a good introduction to crpgs and at least they are finding something that gives them joy.
