Well yeah, lots of Pokemon have unnecessary stats (Sableye's Speed at times, Wobbuffet's Attack stats, etc), but the game needs these stats, so it can make the proper calculations for any situation.
Think of it like this, if Nintendo decided to completely omit Shedinja's Defense Stats, it'd seem normal. However, if a Pokemon like Arbok used Leer or Screech, the calculation would have no variable, and the whole game would likely idle, then crash.
These stats are there to simply keep the game coding in perfect line. =]