I agree. A fetish definitely almost always refers to something uncommon despite what the technical definition is.
I don't think the constant desire to have sex is a fetish because that would be considered an attraction to genitalia and for something to be a fetish it has to be nongenital.It being uncommon is a bit of a misnomer, as it's only the strange things you hear about. A sexual fetish can be to anything, even if it's just a fetish for sex in of itself.
Also, I'd hardly consider feet to be an uncommon fetish, as it's the single most common fetish in men.