It hasn't been revamped because most trucks aren't used to tow, and even the ones that haul stuff in the bed still don't even out the weight transfer. That mixed with fairly low antidive numbers on many trucks.
The modern day equivalent would be 4 wheel abs/traction control
Wow guys. You're schooling me good! Reminds me of swapping ends in my '66 Ford F-250 when I was a kid. I got used to it... Gotta think thru my goals. And the cost/benefit equation.