Once again many folks like to pick at technical point figuring that it's easy to design better (by brute force if necessary)
But what are we protecting? the aircraft for re-use or the passengers for re-use?. You see if you continue to beef up the aircraft you wind up saving only the non-functioning passenger bodies who can't take the G-loads generated by the forces. At high impact loads you actually aid the passengers by expectations of some breakup (fusing?) and in survivable event it also provides a access point or two.
The keys to risk in these events, are avoid trapped by fire or smoke and get out although cut and damaged. With a too strong aircraft you may have a lot more shock trauma (aortic collapse) and stay trapped longer awaiting the fire to take hold)
I vote to stay with what we got now, at least it sometimes work to some advantage.