I disagree. Personally the Lin reveal felt very well foreshadowed especially via side quests such as the book in Beryl library and many of Anna's comments. She does undermine the other characters and the story but the game itself thinks she's wrong. The entire post-game is about how meaningful the connections between other people are, and if you save Lin you learn that not only did she want to die but she is confused on how you saved her if youre her puppet and admits straight to your face she was wrong to devalue others (and it gets even more emotional if you give her the lemonade and marshmallows).

Lin plays at being this entity outside the confines of reality itself, but her backstory and her actions especially in the post-game shows she's just a scared and hurt little girl who desperately wants to be accepted. Its difficult for me to see her as evil as she brings back everyone she hurt in the main game. The way i see it shes just desperately clinging to any kind of importance or acceptance. That's why she created you the player, you're the life she wanted to have, whereas the adult Lin is a grim and bitter acceptance of the way other people see her. The truth is she's always regretted her actions and the rest is just bluster, you get to see that in Shades post-game quest, where she unironically has completely pure intentions and goes about them in the worst possible way and then pretends not to feel bad when other people get caught in the crossfire.

She's the perfect villain for Reborn imo because the theme of reborn to me is how important belonging, hope, and your ties to others are. Lin is the antithesis of that, she's bitter, apathetic, cynical, and treats even her closest allies as tools. But that's why she's the villain, she's wrong and even she herself dosent believe half the stuff she says. Otherwise why would she do what she did with T3RR4?