You gotta look when you wipe so you know how you are doing.
I stand up when I wipe, and have had this conversation before. I can see sitting down, but it seems sketchy to blindly stick your hand near a pool of water that is filled with shit. Also, I am left handed, and often times the tp dispenser is on the right, I got used to standing up to grab some with my left paw.
Interesting though, nobody brought up dingleberry prevention in my last convo. Good point!