I guess if you really think about it, adoring any body part is a “fetish”. It’s just socially acceptable to like tits or ass, and society has deemed adoration of feet as undesirable.
To fetishize the foot is something different.
I would think things that signal healthiness or contributors to increased chances of survival are subject to a biological response, rather than specifically reproductive parts. In which case, a foot devoid of issues can be a pretty big signal of healthiness, for example one not subject to bunions or flat footedness, etc.