The fantasy isn’t that a brooding “tall, dark and handsome” man will come and swoop you of your feet. 

Darcy changes for Elizabeth. She rejects him, she stands up to him, she insults him in a magnitude of ways, both warranted and not, and he takes all of that, and he reflects on it, and he changes his behavior. He tries to be better. Because he respects Elizabeth and he finds her opinion valuable. 

Think about it. A usual response, both back then and today, would be to dismiss Elizabeth as a “crazy bitch.” He doesn’t do that at all, no, he takes valid criticism found among misunderstandings and takes it to heart. 

The Mr. Darcy Fantasy is a fantasy about being respected and having your opinion be valued very highly.