I can see where Dr Krieger is coming from and agree, that often the design work and manufacturing do not take best advantage of alloy over steel.
If we compare a steel and cloth fuselage to a similar alloy with gusset fuselage also covered in cloth- the steel should win. The cloth offers no strength at all, just keeps the wind out. However we look at a truss type fuselage in alloy that is skinned and gusseted where appropiate- the scenario changes a lot. The tubes of the truss are square, with high bonding/ riveting area. The skin on the outside is needed anyway of some type, the interior one is handy for mounting things.
We are now looking at a truss that is sandwiched. The combined strength of the sandwich is considerable. It will not flex, kill the occupants and spring back. It is very vault like, add in insulation and quiet as well. That is for a cockpit, the cage you wish to survive in. A normal tube and gusset rear and tail can still be used to maintain low weight.
The point is we can beef up a fuselage to meet the demands we expect of a steel frame and still build in alloy and have deformable crash attenuation in our design. In theory, we could make it of the best material for each load and crash survival but that often, ends in many different materials. A example would be a steel cabin and alloy remainder or even a steel cabin and glass or a lot of combinations we see in design and that is before we get serious about some safety.
I think the idea of designing for the particular attributes alloy presents and its potential is the key. The spam can, can and will happily give the impression of strength until it kills and acts like nothing happened. The steel frame will bend a bit but is quite solid- it does not takeup the impulse of collision well for the occupants either. We need to design so anything bar the cabin is treated as crush zone, then we can give ourselves the ability to dump the big g loads in crushing the front, the wings breaking off and the tail compressing a bit. But the cabin stays in tact- any additional loads are then transmitted around the cabin perimeter and minimal g loads reach the poor mushy bit inside.
The poor bugger in the pilot seat should have a proper seat that allows for some movement to take up the big loads of a sudden stop. Additionally the landing gear is crush area/ g load shedding. If we a add a small and relatively light alloy structure bellow the structural cabin we can have extra crush zone with minimal weight. This can help protect the pilot for big vertical loads. A steel frame still has relatively unyielding structure and any extra added pieces are still quite stiff to be useful in sucking up G loads.
I see that a Alloy structure can not only be strong, cheap and not too heavy if designed well- the safety for bad days is in the design. If we compare steel and cloth vs a traditional monocoupe we are making the wrong comparison. Neither is ideal if traditional thinking is used. We need to think more of a blend including sandwiched trusses-then we can really take advantage of the material and the ease of manufacture for a safer aircraft.
No matter what materials we use, builders are often stuck with whats available and is it economic?- a very big deal outside the USA where tube is cheap, alloy abounds, epoxy flows from gutters and Spruce just falls next to you. I would expect the most economic material for the vast majority is alloy tube and sheet. So that is what I would choose- if the aim is the most builders getting a aircraft in the air, cheaply and quickly, that if all goes to shite, may not kill them. Use the right grades and follow simple instructions and no specialised skills required. But the design is paramount- no amount of skills will make a Affordaplane a awesome design. But the materials can be used properly, its all in the minds eye.
What the aircraft looks like after the crash is irrelevant, as long as the skin bags of flesh get to walk away. I know that sounds ghoulish but the man who lives laughs the loudest.