Cars are designed to protect the occupants during a crash. There is no consideration given to being able to drive the vehicle afterward.
I agree with your first statement, however if you're dealing with enough force to cause the wheel to come back and slam the occupants, I seriously doubt any crumple zones would work properly. I'm talking low to mid-speed impacts. I've seen cars where in a front impact the front suspension is FUC*ED and the cars have to be towed away. What sets apart a good car and a poorly designed car, IMHO, is one that can still drive away quasi-normally after a fairly nasty low to mid speed accident.
As for aluminum - look at any cast aluminum wheel that costs $300+ per wheel used on sports cars, "tunerz" cars, etc... They will and can CRACK the moment something hits it (another car, curb, etc...) hard enough. Lots of folks that live in areas that have nothing but dirt roads refuse to buy cars with alloy wheels or switch to steel wheels. From their experience, alloy wheels will crack eventually and cause leaks. I didn't believe them until they told me about how they have to refill the tires each week
Steel wheels may be ugly but I've seen them take severe beatings and require minor repairs to fix. Forged wheels can be heavier and you're now delving in the world of form over function.
I know there are other designs that may favor one material over the other, but generally speaking if you use cast aluminum you will need more material to retain the desired strength and even then I have my doubts about their superiority in strength vs. steel.
Sort of a digression, but it's related:
There are engineers at work that boast about Zytel Nylon's strengths/capabilities but I have seen lots of Zytel parts simply crack when you hit them against a object w/o enough force applied (and they intended to use zytel in applications that are going to get hit repeatedly by blunt objects). Don't forget the coolant crossover cracking on the 4.6 intake manifolds... they're made of Dupont Zytel Nylon - the wonder polymer. I had to return 3 brand new Ford PI intakes because the Zytel cracked at several important locations during shipping. And it was packed in extra bubble wrap, newspapers, etc... in a box. Zytel is also used in Thermold/Orlite AR15 mags that crack if you drop them on a hard surface.
I haven't tested the material/design of the Marauder suspension, but I personally wouldn't want tin foil for any of my suspension components. I've seen too much parts/material carnage to give it a try!
