So it really is just the two women are better than one thing?
No ~ It's the two wimmin AND sex. Besides we are amazed that you aren't all just panting to get hold of our flaccid little willies and play with them (like wot we do when we are alone). We are sure that if you do get your hands on our "bits" you will be so overwhelmed with gratitude that you will be our sex slaves forever more and never have a headache, the painters in or any other "reason" to deny us.
And Bi is just an excuse for having your cake and eating it.