Mother Gothel is an interesting figure, as far as Disney villains go. In a lot of ways, she’s the most human, and the one capable of scaring people the most. She’s not evil in the same way as Maleficent or Dr Facilier, she’s not greedy like Cruella DeVil or Governor Ratcliffe, and, truth be told, she doesn’t really have that much badness to her.
What makes her interesting as a villain is that she chooses that path. She had plenty of opportunities to do the right thing, and she never did. And when she says “Fine, now I’m the bad guy”, you know that she never saw herself as such until that moment.
What makes her scary is that there is a lot there that is all too real. She is smothering, she is emotionally abusive, and she is only concerned about herself. Not good attitudes for a mother to have. And yet, there are all too many mothers - or fathers or siblings or any number of other relations - who are the same way. Mother Gothel is frightening because she shows the extreme side of vanity.
Some people say “Oh, she really did love Rapunzel deep down, she was just too caught up in the power of the hair.” But if you look, every time she expresses affection towards Rapunzel, she is either touching or looking at her hair. When they do their “I love you,” “I love you more,” “I love you most” routine, she says the first ‘I love you’ to Rapunzel, and the second one to her hair.
She’s not a witch and she’s not magic, but she represents the end result of human desires to the extreme. And that’s not a pretty picture.