Statwise armour is the same. The perks(mods) are what's different(and therefore unique) I would hate to find armour for all of my classes that was exactly the same or offered the same benefits. Each class was made to fit a certain role and played a certain way. Their exotic armour should reflect that. Titans are already underused because they spend more time hiding behind a rock instead of tanking. Armamentarium is just one of the few things the Titan has over the others....and it actually fits within the scope of what a Titan should be doing