I found this analysis of scifi movie armor by A Collection of Unmitigated Pedantry fascinating.

Armor style is coevolved with the selection environment.

For real armor it's coevolved with the enemy's weapons and tactics, with the ultimate ground truth of helping the wearer be an effective fighter and survive.

For movies it's designed to look cool, look different enough from other movies as to not feel derivative, and to allow actors to move and emote.

These are very different forces that pull them in very different directions.