Are you guys idiots? I certainly don't identify WITH Medea at all, but unlike Psyche has both a goal, aspirations and ability. She wants something, she has the ability to climb to it, and that is much more unique and entertaining of a story than then usual generic Weak to Strong Formula
Medea is already strong, but the fact that she isn't perfect and that she has many obstacles to her goals is what made her interesting. She has the ability to win, but she has to grasp it through all the things that are trying to stop her.
If anything Psyche is the mary sue who got a literal god on her side and made Medea die in her place. Assuming Medea does die here.