Daisy, to me, doesn't seem like kidnapping material. She's just not "girly" enough. Peach, on the other hand, is a damsel in distress to the max. That confused look in her eye, the pale skin, the complete and utter innocence. We can all see her behind bars in Bowser's castle, right? I mean, I can see Daisy saving Luigi, but Luigi saving Daisy just doesn't seem to cut it. She's more sensable and tought, dare I say it...
*waves at CaptainYoshikano*