I have to admit that I've never stabbed anybody either, or indeed bludgeoned anybody with a flanged mace. However, it's a very basic law of physics that any object which hits you will do more damage if it's moving faster, meaning that more force was applied to get it moving in the first place. With a melee weapon, force means strength. It's true that a 2-inch stab-wound can kill you, but if for some reason you are forced to let someone stab you in a completely random part of your body, and it's a choice between a 2-inch and a 6-inch stab, which are you going to choose? That situation is already covered by the Critical Hit game mechanic. DEX may increase your chance of scoring a crit, but STR has a major influence on the damage you will cause with every weapon all the time, apart from things like crossbows and guns where it's totally irrelevant.