More to the point: the women are being used in a way that is completely determined by the user of the app, instead of being given any kind of consideration as people.
If I am staring at a woman's tits - I am certainly giving her whole person my consideration, even though my eyes can only look at one thing at a time. WTF would I do with just a pair of tits?
No, the reason I'm looking is that I probably want more.
This app removes the women's ability to participate in the exchange at all. They have no control and are presented in a way that is completely in control of the user. When you remove her ability to decide how her body is being used, you are not considering her as a whole person. It's not about tits.