Maybe your girls are more open to it... I don't know.
But those with whom I talked, they're reflecting views in their SM group - of course that subject was discussed repeatedly. And that was really surprising, to find that SM girls are much less inclined to tickling than ordinary girl-next-door.
Maybe its due to different ways of looking; when they talked about it as of discipline, or method of SM-play, - dating with girl you use tickling as another communicative way, innocent playng or beforeplay... not more than light teasing. I mean, tickling then is not the subject, just a trifle that don't scare.