The entire appeal of Rei is that she's a lonely, isolated girl who has obvious issues with human interaction and there's the perception (and hope) that maybe she can have a meaningful interaction and eventual relationship with you.
I think a big part of the appeal is that introverts are attracted to her because she's someone they can be their introverted selves with and not have to act fake or "keep up appearances".
Aside from being 10/10/ material, it's because we can see ourselves in her. Her joy, her sadness, her inner struggles. In a way, she represents every human being out there, including you anon. Such is the beauty of the characterization of Rei.
This one's for you...