Simon of course will answer this, but i have asked that same question before.
The cost to make the eye covers would be stupidly high. Basically, would you want $100+ eye cover set, nust for thd sake of matching the anno? The Empire plastic ones are cheaper, durable, easily source from Empire, and though cheap looking(plastics will always hold that astethic over metal), are much better value than a milled eye cover. If you look at Empire, they used the pladtic for a reason, to keep costs down. If you want an eye cover, it would be the inverse of that cost.
But i am sure Simon will tell it himself, when he has time.