It's used too much. Since I have a huge tickle fetish, tickling turns me on and is very arousing. Couldn't really be catagorized as being "torture." At least not for me, just a huge sexual rush. Both me and my girlfriends enjoy all of the teasing and feathering that we do to eachother when we are playing around while we are in bed together.
I can see where if a victim is horribly ticklish and quite fearful of it ... the approaching doom of being tickled by an interrogator as a way of torture or punishment might be hard to withstand. I know from experience that sometimes just the taunting of a 'lers fingers or feathers over a 'lees body or tickle spots can be enough to make the strapped down victim plead and scream for mercy, maybe even begin laughing, always immediately fearful of the intense tickling that is about to begin ... eventhough it hasn't yet. Maybe that's a better way to imagine tickle torture.
Much of what I've seen in tickle magazines (before websites came along) and in all of those old Calstar or Prestige fetish videos really is not tickle torture. It was mostly just "tickle play" between partners. The rope work and the bondage was never very good. Yeah, sometimes feathers were involved ... but not very effectively or convincing. With my girlfriends, I'm a much better tickler with my feathers on their naked bodies. In my opinion, much of what has been put out there as "tickle torture" videos (DVD, old VHS, online homemade clips, even the fetish company porn stuff) doesn't even come close to really showing true "tickle torture." I so totally love all of the lesbian F/F tickle play video material ... but most of it is always like wrestling on the living room floor with no bondage and if there is some bondage, ropes, it's never done very well.