utter lack of left-handed controllers
No kidding. This has annoyed me for years. I bought Battlefield: Bad Company for my PS3 only to find out the game didn't have an option for southpaw mode...nor does Oblivion, or inFamous, or Bioshock. I finally modded an old sixaxis to use the opposite stick's input...now if I could only figure out how to swap out the action buttons and the d-pad.
Numeric stability is probably not all that important when you're guessing.