That's the trade off when you reinforce your frame to support a winch or add a heavy steel bumper.  The original crash engineering is changed a little.  I'm sure at a higher speed, the frame would crumple along the same engineered designed lines, but the kinetic energy will be directed "somewhere" a little different.  How does the heavy front skid plates affect the "crush zone"?  I don't know the answer to that one either, but I'm going to guess the front frame becomes a little stiffer as a result of it being added.
Most new cars today are "certified" to withstand "impacts" at speeds up to a 
whole 2.5MPH without suffering damage requiring repair.  2.5MPH 

!!?   That tells me that virtually any contact with another vehicle is going to cost some serious bucks. 
I don't care to go back to the days of solid steel dash boards and 10 gage body panels where after wrecks, they just hosed the blood out and replaced a fender and resold the vehicle, but I prefer to have a little more robust bumpers than ones that can only handle a 2.5MPH impacts before serious body repair is needed.
I've often wondered if the SRS air bags in Buster would even deploy in a frontal or rear impact. 

   He 
is going on 15 years old now.  I don't plan on them deploying  properly and therefore I work really hard on 
not crashing into another vehicle.  I know "stuff" can happen, but I work really hard on mitigating the outcome.