why did men play womens roles in shakespheare plays?

Performing plays developed from two sources, the church and groups (or guilds) of workers, both of which were male domains. Theatres were closed during the Commonwealth and re-opened at the Restoration of the Monarchy in 1660. In the new cultural climate actresses were employed to play women's roles and the transvestite tradition quickly died out except for comic parts such as the witches in Macbeth and the nurse in Romeo and Juliet.