@superguy1591: Didn't know it dated back that far but still why cross dress? Can't a guy be funny without tucking it and twerking for the masses?
It's viewed more as it's own comedy niche, like slapstick, improv, or prop comedy, or miming. The costume is used as a device to mock principles of gender identity and sexuality. Now that there are an abundance of actresses for female roles it's no longer a necessity for the theater but fans of the niche keep it alive