>>2163
Even in earlier revisions where Aelfwine is the disseminating source for the Red Book, there's still no plate. Even in the Fall of Gondolin, written before the very concept of a 'Third Age' is liable to have existed in Tolkien's head, the inventory of Gondolin lists plenty of mail and halberks but no plate armor.
I think it's very unlikely Tolkien ever intended the Noldor to wear plate. The Numenoreans have a better case for it. Full plate armor (e.g. not overlapping plates like lorica segmentata or the dendra panoply) developed on the battefield according to changes in weapon tactics and technology. Namely, the rise of an entire class of skilled users of ranged weapons (first longbows and crossbows, then early firearms) that diminished the utility of traditional mail armor in pitched setpiece battles. The Noldor of the First Age certainly have the metallurgical and infrastructural capacity, but the need is questionable.
Neither Morgoth nor Sauron's orcs are known for being particularly skilled with ranged weaponry. The use of poison and barbed tips suggests that they're not particularly good at hitting their foes, that they need to make every arrow count.
Pitched setpiece battles are also rare in the First Age. There's only six of them, across ~580 years. One doesn't feature the Noldor, one comes just after they arrive from Valinor, another has literal divines plus the Vanyar backing them up. It was far more common, especially during the Siege of Angband years, for Morgoth's orcs to use skirmish and raid tactics instead of devoting resources to pitched battle. In such a circumstance, chain armor has far more utility than plate armor.