I don't get this, I don't see anything convoluted or half-baked about this. To me it makes a lot more sense than it did before.
A 'weapon' is a thing, and item, a tool for destruction. When someone says "I found a crate of weapons", no one expects to see a bunch of cut off hands and feet and knees. A 'weapon' is a gun, or knife, or club, or sword, or..... Thus it makes sense to make a 'weapon attack' with an actual weapon. When you cast Magic Weapon, its on an actual weapon. When you 'silver a weapon', its adding silver to an actual weapon. When you fight with 'two weapons', it means a knife and sword, or two whips, or whatever.... it doesn't mean a boxing match.
An Unarmed Strike is called such because you are *unarmed*, meaning you have no 'arms', meaning you have no weapons. To try and claim that a 'weaponless attack' is somehow really a weapon.... that is convoluted. It is non-sensical to insist that a 'weaponless attack'(AKA Unarmed Strke) is a type of weapon.
So, to me at least, that all makes sense. But we also all know that a fist (or elbow, or foot, etc) can also be used to cause damage, similar to how a weapon works. Hence the rule/errata clarifying that you can use an Unarmed Strike when making a Melee Weapon Attack. That seems to follow everyone's common experiences and knowledge.... I don't see how that is at all convoluted.