Feet are the lowest part of the body. "Greeting" them with my mouth, tongue, face (basically the highest parts of my body) is a and always was a very strong sign of devotion and submission. That's essentially why I want to do it.
Furthermore, feet are the body part that sweats the most and can easily get an unpleasant "odor". Society portrays them as a "dirty" area of the body. Feet (or at least shoes) are also always in contact with dirt from the ground they walk on. That is why it takes more devotion and submission to, for example kiss them, then it would to kiss a cheek or some other part of the body.
And even if you have a foot fetish, you wouldn't want to kiss, lick, suck, ANY pair of feet, would you? You would still be picky and make sure they fit your "taste". You could still kiss the hand of (for example) a lady you find old, fat and ugly as a gesture - but would you really want to drop to your knees, take her shoes and socks off and kiss that person's feet?
Sure, many women take so very well care of their feet and make them look really nice - often even a completely non-kinky guy wouldn't have a problem with giving them a quick kiss. But would he want to be trampled underneath them, have them rubbed in his face real hard, maybe after a sweaty workout, or after walking around the town barefoot? I think it takes an actual sub for that.
I don't even consider myself a foot fetishist anymore. Even though I absolutely am turned on by many "activities" involving women's feet, it is so because of the above reasons, not so because of a fetish (Freud and modern psychology would also never call a strong interest for a certain part of the body a fetish). There are even some things commonly found on foot fetish websites, like for example footjobs, that I absolutely don't understand and wouldn't even be interested in.
