Because Daisy doesn't have a history of being kidnapped all the time by the same guy, who professes to love her... and because, unlike Mario and Peach, Daisy and Luigi's relationship is very out in the open. I mean... Daisy LITERALLY commissions public works like giant golden statues of her and Luigi dancing in order to show her love (look in Mario Kart Wii at her racetrack for examples). This is opposed to Mario and Peach, who are actually rumored to finally be tying the knot (Peach has a Wedding Ring on in Super Smash Brothers Brawl), but are still very low key about everything.
#16
Ravenpoe
Bowser Jr. and the Koopa Kids had to come from somewhere. I mean, unless Bowser is hitting Birdo* on the side.