Always glad to find M/F , some F/M...
Producers know what sells the most --- though it's interesting that
some producers DO sell more M/F (though they might not be the norm)
which is a relief for me, since I really like the heterosexual interaction,
mostly M/F, some F/M --- I don't like f/f or m/m though I'll look occasionally
Might just be whoever's most vocal here & in the video section, but again I'd guess the producers know from sales & feedback
(And polls I guess, though those might not be the most reliable...)
But I can also see how it might not be sexual (though it involves touching & stimulation, etc.) ---- Some may view it as a
rollercoaster ride ---
Big thrill, wild ride, but nothing sexual....
I can see that if you're tickling someone you find unattractive, especially ---- the appeal might be in tickling their feet or whatever, generically,
if you come across

such as --- maybe
Fred Flintstone's feet sticking out of that fence
😛 You want to see them tickled but...
(I almost died when that appeared on TV when I was a kid)
Or any annoying female neighbor if that's your preference ---- (or Olive Oyl) the choice might be "sexual" in that you want to tickle a woman, for instance, since you may not want to touch a man,
but if it's someone unattractive ----
I'm guessing it might just be the feet themselves, or underarms, whatever tickle target is found to be vulnerable, sensitive, (preferred) etc, which are of interest, not the person overall
(though I guess that could also be said of those who find this sexual, they also focus upon certain body parts often).
But picturing Fred Flintstone ---- I can see how it can be a thrill without being sexual
😛