Well, that's true, but at least armoring the the illagers will make them more difficult to fight, so it's not completely useless.
For example, the Evokers' low health always bothered me since i consider them to be sort of minibosses, you can give them armor to simulate higher health ( i know that when a player has diamond armor it's like he has 36hp, every armor point absorbs 4% of the damage so you can do health + how much percentage of the damage your full set absorbs to get th effective health that an armor gives, ex.: 20 + 80% = 36)
And, at last, it could be also interesting to create some minibosses to wonder around in the dungeon with enchanted weapons and armor (for example a vindicator with iron armor and a Fire Aspect axe)
