Sure, we generally want to use the larger muscle groups (e.g. legs' muscles generate more power by themselves than fingers') but both seem pertinent to "real" self defense...particularly if you consider whole-body self-defense or defense involving firearms. While they're a small part of the overall force generation, the fingers and hands can add the needed edge in real self-defense and, I presume, can convey the whole-body force sought after in internals.
I agree that the simpler techniques are generally the most effective. The fewer operations needed to displace your attacker the better...and from what I've seen casually, at least in the one-on-one setting, I think MMA shows this tendancy toward a handful of basic self-defense maneuvers which typically win. This doesn't mean the other techniques are irrelevent though.
Also, I'm no expert so I'm probably missing something key, but my impression is the internal arts would describe themselves more as whole body balance, not single-leg balance.
...Now I'm curious if that's what is meant when describing one-sided weighting?
Basically just guesses, but there's my 2 bits.
All human movement starts in the legs(sports,martial arts) ect.Obviously!.
Taiji term double weighted??
Double weighted is just that...a 50/50 stance.
A F..ing no no!! IF you have good single leg balance it is very difficult for someone to throw you.You are not where they thought you were.Just like lifting something,you find the balance point first.but if that balance point keeps moving it is hard to find the centre(hara,dantien).
This is what is ment by moving from your centre....NOT your waist.
And probably why many Aikidoka's move like Robby the robot.
Moving your balance point is like trying to lift a bag of water.Difficult.
As you move from one foot to the other(never ever stop moving)someone trying to throw you,push you,lock you up has got problems.because you won't stay still.
Internal arts are all based on balance and proprioception,so you learn in abstract fasion,and carry on learning.
If you need to defend yourself,you will attack the two primary pressure points,automatically without thinking.