Personally, I don't think that happened in the crash...
I think the Slybolt just spit that 2-stroke off in disgust.
I'm just busting on you. But I see your point, a decent piece of plywood would have been a big plus. And a better bracing system would have helped. But I also stick to my guns in saying that today's planes are completely re-engineered from the way they were 10 years ago.
You have a legitimate complaint about the firewall, but someone else may have broken a stab and said, "If it were fully sheeted like the KIT version was, it wouldn't have happened". And someone else might say, "If they had beefed up the landing gear area, etc, etc."
A few years ago when 3-D came into vogue, the industry went "Light Crazy" (Just as now they are going "Electric Crazy" ). Look at how planes are engineered nowadays with their lite ply interlocking framework. It's strong, yet light and totally different from the way we used to build. But it has to give up one thing to gain another.
So yes, they could have made a stronger firewall, and that would satisfy you, but it wouldn't help the guy who ripped his landing gear off. If they beefed up all of the stuff that everyone had a problem with, we're back to a plane that weighs a pound heavier.