Frankly if it were not for my set of ironmind grippers my left hand which statistically should be stronger than my more coordinated right would be relagated to the mediocre 40lbs of gripping strength it had 3 years ago.
When I was 2 years old I tripped and caught myself on the glass window of a screaming hot woodstove giving me third degree burns. The doctors assumed I would never have the use of my hand because of the nerve damage. They now figure it at about 60% damage.
So what's my point? Isolation movements were necessary for me to improve the gripping capacity of my left hand. I was not contented by the fact that when I first joined the military I had to tighlty wrap my rifle sling around my hand in order to shoot my rifle. I was barely able to deadlift anything without straps and my grip would fail immediately when pull-ups were attempted.
The works of John Brookfield put the concept that when necessary, isolation has its place, sometimes I even forget that. Hell my hand still gets MEAN shakes when I'm stressed. (or maybe I have parkinsons, lets not think about that)
I think Ido's point of structural balance is a valid one that I've got to look into more thoroughly.