I would understand people not turning in firebloom because that would be a ripoff, but copper bars? What kind of profit are you expecting to gain with copper bars? If I started to farm Deadmines 24/7 I would reach 3k copper ore pretty fast, and there's no point saving it so I'd just hand it in along with the linen cloth.
I'm not really sure how people can be surprised over the rewards that certain items give, it has always been on the table. If you wanted value then maybe you should've saved up 3000 arthas' tears or runecloth and handed them in for 10 marks each.
The incentive of turning in items is opening AQ, any items or rep you get along the way is just icing on the cake. And yes I wouldn't be surprised if certain people are hoarding items to hand in so they can decide when the war effort ends and when the Brood of Nozdormu rep farm can begin.