He wants to satisfy some fetish

Izuku has always been very focused on the heroic world, on studies and more recently on exercise and health, he never had the time or much inclination to explore himself sexually, never having a girlfriend or even watching much porn.

Now that he is on the path to becoming a hero and has already managed to make the world a more peaceful, fair and safe place, what harm would it do for him to explore this side, to explore his few fetishes that he had in his most intimate moments.

Now he could change his body to something he thought would suit him, more masculine, more feminine, or just leave it as it was.

He could also make a good romantic partner more easily revealed to him, so he can have a girlfriend, or use it to find girls who are more forward and easy if that's what he likes, maybe something more kinky.