The other point of training the off hand is simply to be familiar enough to defend yourself if you find yourself in a position where your primary hand is not readily available for fighting. Whether it be injury, restrictive space, etc, then you're not completely helpless.
Myself, when I'm at the shooting range I always empty a clip or two with my left hand. At different times playing pool, I'll shoot with my left. It's always kind of fun to catch guys with a stiff jab or hook when sparring. They usually don't expect it.
I guess the other thing to keep in mind is that training the off-hand for offense is that it increases your defensive capabilities.
It doesn't matter if you agree or disagree
... As long as I don't bore you and I spark a moment of thought, my goal is achieved
Queng leon queng tigre ecu tacacut, queca pa? - Pampangan Mandarigma Motto