True that.
Working each side of the body (arms, back, legs, etc) individually can give a better response to development and strength,for the BB'er or any lifter in general. Also insures a equal balance to both sides of the body, though one side will most always tend to lag a bit behind the other. All this can transfer to better strength when using both arms in a lift ..even squats included. To me, one arm lifts add better total focus on the exercise I'm doing: one arm DB Hi-pulls, DB side presses, DB lateral raises, DB rows and even one arm DB benches at times. Never much that into machines, exception being the Nautilus equipment.
Athletes tend to focus on this as part of training. I also find that one arm chins (negative or positive) affect total strength and development quite well. After a while, plates can be added to the one arm negative chins.
Good luck.