The problem with going directly to the battery is that if something were to happen up stream (wire kink, etc) then you have a direct short on the battery and a recipe for dissaster. If you caught it in time, you would need to hurry and pop your hood and un hook the cable from the battery.
My Warn 16,500 lb winch is hooked up directly to the side posts of my Optima yellow top - even though I know the dangers of doing so. Point being, know the dangers yourself and choose your best method. I'm sure just about everyone has theirs ran directly to their batteries as well.