She's far worse than you make out in your OP, OP. She doesn't educate her - she leaves her in a tower with some books and paints and Rapunzel educates herself. She never sees her as person - when she says 'I love you most' she is stroking at and staring at her hair, not her. Her little jabs and snipes are textbook narcissistic mother - you're chubby, you're guillible, you'll never survive without me, I'm all you have, never leave me, you can't be out there alone.
Then gets nasty at the first boyfriend scenario - "Why would he like you?" and "Give it to him, watch, you'll see / Trust me, my dear / That's how fast he'll leave you."
I found her very hard to watch as my mother had said all this and more, and to think that it was clearly a common enough occurence to have formed a character over was quite startling. You're fat, you're ugly, everyone's laughing at you, you can't ever move out, you can't leave, you'll never get a job, you're too stupid, you need me, you stay with me, oh, a boyfriend? He's just using you, he will leave you...
And then, yeah, as you say, by the end you relaise Rapunzel simply isn't a person to her at all, she genuinely has no feelings towards her other than as a source of the spell.
It was a tough one to explain to my kids, that's for sure. They couldn't untangle the warm, friendly scenes of brushing the child's hair and talking about birthday presents, and the hug, with the villain at the end.
I don't really see Elsa's parents as bad at all - Elsa needed to hide the damn ice powers, she couldn't control it and was running the risk of killing someone or being discovered and cast out/burned as a witch. Concealing it worked. Yeah, OK, love and happiness worked too, but she'd almost killed their other daughter, and it was unlikely Elsa would have been able to relax from that for a long time.