oh those are a girl's alright...here (like it'll help you decide 🙂
hmmm...scientifically, cos' observation may just hold --- flatfoot means more contact on the ground, more pressure, friction, disensitize, thus less sensitive. High arches means more sensitive arches 'coz of less contact. Does that make sense? But honestly, i never thought of it that way before. Ticklish to me (or at least "tickable") are soft looking, smooth, and pinkish on the right spots --- balls, heels, toe pads but the arches are always pale.
I'm not surprised there are not too many takers of D. Yet, that's the first spot we see when someone's walking in mules, flip flops, sandals...then the imagination begins 🙂