Originally Posted by
Mjollnir
To me, it seems a lot of the core mechanics of the game are based on classic D&D (eg if you reduce your stats right down at lv1, removing racial bonuses, you'll get straight 18 scores).
The armour is the same - light/medium/heavy. 'All Classes' can use light armour, as it's essentially just clothing. Restrictions are put in place for medium and heavy armour because you need a degree of training in order to wear it effectively in a combat situation. This is the concept in D&D and it's transferred over to FFXIV.