The saggy rear end Toyota's was just an example of how silly it looks. A 500lbs/inch leaf spring is just that - the spring flexes 1" for every 500lbs of load. That's why your truck with a 1,000lbs payload has 2" of rake so that it sits level under load. All that lifting your front end does is ensure that your suspension geometry is out of whack when the rear end starts sitting lower.
Even passenger sedans and wagons have a slight rake for load handling and better road manners (including aerodynamics and fuel economy).
I could actually go one step further and say that once you're in a full size truck you're not buying a 4x4 for offroad use and you can ditch the lift (front and rear) all together but that never goes over well...
