From my experience it does aid in tickling, i dont know if it actually makes them more ticklish.
I think it really helps tickle toes due to the lubricating quality of it. When they clench their toes it makes it hard to tickle them, but the lotion allows for your fingers to slip through their clench without hurting them and tickle away. On the bottom of the foot I'm not sure that it really makes them more ticklish but it does give you good opportunity to tickle when you lure them in with a lotion foot massage offer and sneak tickles :]