Because in male circumcision except in unusual cases, only skin is being removed and does not interfere with the function of the penis.
With female circumcision, a sexual organ is being detroyed and not only removes any ability to reach an orgasm, can cause severe lifelong pain in urination as well as just having sex.
Do they go inside and cut out the girls G-Spot too? because the clit is not the only way a girl can reach orgasim.