I actually wrote a while ago, requesting advanced / magical versions of leather (Ranger Armor, Assassin Armor, Marksman Armor), chain (Steelmesh Armor, Masterwork chainmail, Barbarian Chain) and robes (Archmage Robes, Emperor Robes, Warlock Robes) so we can have a sense of progression even for those troops or heroes who don't have the plate mail skill.
These armors do not need to improve the defence but can be used to boost other skills (for instance, Ranger Armor can give greater movement, Assassin Armor can improve chance to crit and Marksman Armor can improve Accuracy) so we have to choose between them.