Quote Originally Posted by Iscah View Post
Gear doesn't need to make body parts "invisible" to avoid clipping – it simply replaces the body model entirely. This is the case for everything, except that usually it is replacing each piece with a gear model of the same proportions so you don't notice the switch. Things like bare arms or hands are modelled into the gear piece as well.
I don't know all the logistics behind 3D modelling as I know it from a minor point of interest at best, however it is possible that it was just more feasible to make the thighs invisible than change their shape either due to time constraints or just whatever quirks the robe itself may have in its design.