Why did Michael Jackson were eyeliner and mascara?

Michael Jackson had a skin disorder called Vitiligo that made his skin turn white in patches. He underwent depigmentation to give his skin a uniform color.

He had surgery on his nose after he fell and broke it during a dance routine, during the operation to have it fixed he had it reshaped/made smaller, that surgery resulted in him having breathing problems to he had another operation to correct it, once again choosing to have it made smaller. He chose to make it smaller because he had a poor self image regarding his nose due to his father making fun of how his nose looked [see Related Link for details].

He had a chin implant to look more masculine.

See the Related Link below for a photographic history of the changes to his face.