The Lower Abdominal Exercises: Are they helpful?

So you go to the gym and everyone is doing all of these crazy abdominal exercises.  Different versions of side bending, crunching, leg lifting, hanging twists, all in the attempt to "shred" different parts of their abs (to be perfectly honest, they are "shredding" their low back...and not in a good way.)

I was in discussion with a few people trying to understand where this epidemic of abdominal exercises.  Are there really any abdominal exercises that can help sculpt the "lower abdominals?" 

If you were to ask me if there was a way to "stress" the lower abdominals to a greater extent, I would not fully disagree with you.  However, if you believe you are "isolating" the lower abdominals, I would vehemently disagree with you.

The entire abdominal group (transverse abdominis, internal and external oblique, and the rectus abdominis) are innervated by the thoracoabdominal nerve (anterior branches from T6-12.)  To simplify, the abdominals are all controlled (collectively) by ONE NERVE source.  So if the abdominals were to turn on, the ENTIRE abdominal group would turn on.

With the abdominals being "wired" together to all turn on at the same time, shouldn't we be using this to our advantage and training the ENTIRE abdominal musculature functionally?  By functional training of the abdominals I mean using the abdominals to BRACE.  So why not do pushes, pulls, lifts, carries and drags.  Why not practice stuff you do for your sport or stuff you do for work.  Pick boxes up off the ground, carry a heavy bag, do a bunch of push ups or squats.  These are all good abdominal exercises! 

 
If you still believe that you can isolate the lower abs, I would like you to show me a "Long head of the biceps" exercise that isolates the long head of the biceps.  If you can prove to me you can isolate the long head of the biceps, I'll may believe that you can isolate lower abs (but not likely!)