I can't find fault with anything you say, Stitchbitch. But are we not throwing out the child with the bathwater?
In my world (yes, I often hear that there are parallel universes, with no link between them
). So in my world, a helmet - any helmet - competes with wearing no helmet at all. Even pilots who own a helmet, and wear that helmet for certain jobs where it is either a requirement or at least common to wear a helmet (e.g., EMS work at night), tend to not wear the helmet on other jobs (e.g., flight instruction).
I am not sure what kind of mega crash you intend surviving using a helmet that is to your liking. But can one not argue that in many cases the job of a helmet is already to protect the pilot's head in a
non-violent crash (e.g., dynamic roll-over) from colliding with the cockpit structure? Thereby preventing skull damage, cuts, face and eye injuries. Besides this being a benefit in itself, keeping the pilot conscious gives them a better chance to extract themselves and their pax from a burning or sinking wreck.
Also when it comes to bird strikes, would you not agree that vizor down at all times dramatically increases the chances to maintain control of the a/c, despite the Perspex pieces, blood, guts and bird bones hitting your face? Could one not look at a helmet mostly as a mounting structure for a visor, regardless really what make of helmet.
In that vein I however fully support your warning against gimmicky chinstraps (or chinstraps worn loosely, a la Pilot Yellow). No use, even in my much more limited use cases, of a helmet that flies off your skull at the moment of impact.
Let's agree that following the 80:20 rule even a simple bump helmet with visor offers beneficial protection in 80% of the accidents. (100% being totality of accidents where an
ideal helmet would save your bacon.) Certainly no reason to suggest that wearing no helmet would be better than wearing any of the helmet types that you suggest to "absolutely avoid". It is all relative...