I'm not quite sure what you're trying to say. You mean armour in general doesn't drop often. This false...armour drops quite often...you just don't have the need to infuse it because they're all the same. You'd just equip whatever is highest and move on. Weapons, on the other hand, is quite different. You can get a awesome perk roll and you'd want to infuse that and keep it. You can get weapons with perks for PVE and PVP. The upgrade use of weapons parts are significantly greater than armour parts for this reason.