Answer?  The lawyers are driving your van!
    Vehicles are designed to have understeer, on the advice of the legal
experts from the car companies.  While it is generally accepted that a bit
of minor over steer is much more beneficial when trying to control a car
driven at or slightly over the limits of traction, the legal wizards have
deduced that automakers can limit their liability by making cars that will
plow right off the road, front wheels first.
   Then, in court,  their council can say..."see, the driver simply drove
right off the road, because he was going too fast or not paying attention"
Anyone who's over-driven a "piggish" understeering car knows full
well...once the front wheels break traction, you just become a passenger..
  In a vehicle with some oversteer (the rear end may lose some traction, but
you can still steer with the front) you can still control the vehicle..but
once you really lose it, the rear end comes around and you spin off the
road...The legal guys HATE that, because the other legal guys can
say..."Hey, that car spun out, it wasn't my client's fault, it was the car"
and win cases...
  So, we get these designed on purpose plowing cars..or in the case of a
van, we get odd-ball tire pressure specs designed to make the front let go
first due to under-inflated tires ( for the load)  maybe..
  Nice of the lawyers and the judicial system to give us "less safe"
understeering vehicles to drive so they can cover their own butt$..
  My opinion only..
  Don Hanson