It's really not all that freakish, is it? It's just "sensory play." It's akin to touching, caressing, massaging, a few little swats on the bum. These are all things that most people like to do, at least in small portions. Heck, a LOT of people are even into light bondage these days, too, or at least understand why it might be exciting. I guess the point where any of this stuff might be considered freakish is when it goes from "light" to "intense" or "obsessive." You don't need to break out the leather and the chains to have a good time with tickling... do you? I mean, I know a lot of us are into the intense stuff, but you don't start there with someone... you work up to that level gradually (if you sense they might be okay with it.)
I guess my point is, as fetishes go, I think ours is pretty tame compared to some others that are out there. If you tell someone you have "a fetish" they're going to imagine all kinds of crazy stuff that's probably far worse than, "oh, he enjoys tickling."