I can understand the issue with feeling "left out".
Details just do not add up, though.
UB fans make it seem like a foot-fetish conspiracy: "ach, those pesky foot fans are trying to convert us all! Flee for your dear lives!!!"
It is just a feeling, but I think some tickling fans are not bothered by foot contents themselves.
What is bothering them is being confused with foot fetishists, whom they probably consider... less proper, shall we say?
And the issue here is with fetishism as a whole.
When we join a fetish site, they tell us that, as fetishists, we are sisters and brothers in arms [or legs, or feet, or whatever].
While having a fetish might make us more tolerant and aware of other people's kinks, it does not mean that we have to embrace anything fetish-related.
You consider armpit tickling your fetish? Fine with me.
You find foot-contents boring or gross? I can live with that.
Being a fetishist means you get turned on by some particular situation or part of the body - often to the exclusion of everything else.
You can't change what makes you tick, and what makes you sick.
So, when somebody tries and tells you: "you have a fetish, so you have to like mine too because we are kindred spirits" that's just pure nonsense.
You have the right to express your likes and dislikes - as long as that won't disrupt the forum harmony [too much] and won't ruin your fellow users' fun.
Just my 2 cents...