Here's why:
* Driven by revenge: Li Mei's primary motivation is revenge against the Lin Kuei for the destruction of her village. This fuels her actions, including joining the Deadly Alliance and potentially harming innocent people.
* Manipulated by the Deadly Alliance: She is recruited by Shang Tsung and Quan Chi, who manipulate her rage and desire for vengeance. This suggests she may not be inherently evil but is vulnerable to exploitation.
* Redeeming qualities: Li Mei shows some compassion and empathy, particularly towards Kitana, whom she initially distrusts but later develops a bond with. She also displays loyalty to her friends, even defying Shang Tsung in the end.
Ultimately, Li Mei's morality is left open to interpretation. Her actions are fueled by a powerful desire for revenge, but she also shows signs of redemption and compassion. It's up to the player to decide whether she is ultimately a good or bad character.