Frankly, the fact that D&D 5e not only lacks Touch AC, but combines all AC for all body parts into a single number, makes it impossible to challenge players. There should obviously be separate torso, leg, arm, and head AC, modified by stance, combat conditions, and zodiac sign, and a wounding system deep enough to account for where you struck your opponent, with what sort of instrument, and with how much panache (it's unbelievable that after all these years, D&D still lacks a panache system). I think we can all agree that any combat system that treats the blow of a club to the thigh the same way as an arrow piercing a chain hauberk and tearing the pectoral muscle can hardly be thought of as sufficient to provide a challenge to the players!
And what of the eventual toll that all this exercise takes on the body? I have scoured the rulebooks for determining how to adjudicate the effect casting too many spells has on the manual dexterity of a wizard. Rules for acquiring arthritis and carpal tunnel syndrome are strangely absent from this game, no doubt evidence that everyone from Gary Gygax to Monte Cook to Rob Heinsoo to Mike Mearls believes that anything between accurate modeling of the long-term effects of excessive finger ballet and nothing is BadWrongFun, and merely wish to inflict suffering and humiliation on us poor players.
