Theres something very perverse about cutting a swimsuit to show a girls tits and cunt. Perhaps it is the reveal of what is usually covered but also i think for many guys it confirms all that is important when choosing a fuck partner - face, tits, vagina. All else is supplementary. By revealing only tits and cunt though the swimsuit the film maker allows his masturbating audience to concentrate on only the parts of the gorl that excite his penis