Well, I've had the good luck to have been tickling a variety of women over the last 29 of my 37 years...and in my experiences I've found the women with high arches to be more ticklish, not to mention, more attractive to tickle. LOL
I've had tickling in every relationship I've had with females. My ex was one of those with low arches, and wasn't very ticklish there at all. It wasn't a good situation since feet are one of my fav targets. My current girlfriend, who's into tickling, and I'm marrying this spring, has very high arches, and is very ticklish indeed.
I believe that many of the most ticklish areas on the body are ticklish because of the lack of contact they get in everyday life. Since the lower arched feet get more contact through walking, they may become a little desensitized. It also goes along with a post earlier about flat footed gals having ticklish toes. It's what doesn't get that regular contact that is more likely to be ticklish in my experience. It's just my theory.
~erikasknight