Your example does tend to prove a point, that being that even when a certain class of weapons are prohibited, people will still seek out some sort of advantage by arming themselves with whatever is available and proven effective rather than do without. The Brits may very well be once again reduced to sticks and stones, but they will always resort to possessing something more than fists and feet, until that is all they have left.

But more to the point, I don't think anyone can rationally argue that self-defense is akin to retribution. Pre-empting or at least preventing criminal activity by the use, or even implied use, of force is not the same as hunting down an enemy with intent. Likewise, I'd say you would be hard put to find evidence supporting the argument that violent crime is abated simply by restricting access to certain classes of weapons. In fact, here in the US, we have a rather robust body of evidence that would lead one to conclude just the opposite is true. There may be cases where violent crime diminished in a given geographic or social area, but I think the true incentive fomenting such a reduction would likely be the result of other factors, with restrictions on weapons possession being more of a consequence than a cause.

From a survival perspective, I would say it only makes good sense, then, to be properly equipped with a suitable means of defending yourself, or at least being able to reliably sell prospective opponents that such is likely the case.

On your other points, I will agree for the most part. However, it seems many more criminals than you might expect encounter what I can only conclude is a Karmic calibrating event having virtually nothing to do with their apparent intelligence, or lack there of, thus supporting the contrapositive argument to an old cliche, wherein it may be better to be below average than unfortunate!!!