Yes this kind of breaks down if your PC is in fact a 50 year old out of shape person with terrible physical stats across the board. There are valid archetypes you could be going for where that'd fit, and of course you might find such a PC stuck fighting a professional combatant like a ganger, mob soldier, etc. But you won't find that happening often, not unless you're an idiot of a player who refuses to keep a clearly non-combatant kind of runner out of close combat. Anyway, the point I want to make on this contingency is rules don't inherently need to address exceptions to the norm. "Ok, your runner lacks a Juicer's Strength? And simultaneously also lacks a Ninja's agility? Fine, your DV is penalized." Or, if you're reluctant to impose non-explicitly stated penalties (i.e. "house rules") you can work within what's explicitly provided and decree that a fat, out of shape would-be-melee-combatant just automatically is giving away circumstantial edge to everyone he swings at.
So what you're basically saying is that the system falls apart when and you think that can be written off because it's an "exception to the norm". Have you forgotten that extractions, AKA "go kidnap this non-combatant", is one of the major run archetypes? And that is to say nothing of any other scenarios where a non-combatant will fight out of panic or desperation. Why shouldn't the system be built to handle a fat nerd being forced to knife-fight a SAS commando?
An agile elven noble who is a master duelist with a rapier is just as equally deadly as a bulked up troll merc who has mastered his use of an axe.
All that was represented in previous editions by both strength and net hits contributing to melee damage; both the raw force and how you apply it matters. By removing strength from melee damage, 6e does away with the importance of raw force.
...thank you that is what I was getting at. In just about every RPG I've played, strength (or in the case with WotC's "finesse" weapons, dexterity) figured into melee weapon damage, be it as a bonus or flat base.
It basically comes down to why bother with melee weapons (save for the monowhip and for adepts, a weapon focus [do you really want to punch that fire, toxic, or radiation spirit with your bare hands?]) when bare fists and bone augmentations can do more damage?
I was going to give another analogy but why bother, suspension of disbelief seems to be the accepted mechanic in this case.
Looks as if it's time for the "Kid" to sheath the Katana, holster the 6 guns, shoulder the rifle, and ride off into the sunset on this one.