Just a minor point here I want to put out. I'm not saying a token system or dragon scale-type system is a bad idea. I am explaining one reason why devs may not change all the previous quests to use such a system.
First off, I do realize the game is not completely logical story-wise. Many different groups have killed the same villians again and again, and run around with multiple copies of the supposedly unique items that the villians had. Seriously, how many special napkins or swords or loincloths would one evil creature have?
That said, to go along with the story, many of the raid rewards are supposed to simulate defeating the big evil baddy and then taking his sword or cloak or other special item. It won't always make sense FOR THE STORY to be able to collect some type of Chuck E. Cheeze tokens which you bring back to town to some type of 7-11 where the owner pulls out his selection of Reaver Swords, Dragon Orbs, and Thor's Hammers for you to take your pick of.
Because of that, the devs probably won't change the existing raids to such a system quickly or easily. They still have writers who work on the game's story. It makes sense to collect adamantine or dragon scales and have someone make an item from them. It won't always make sense to collect generic tokens to turn in for any "one of a kind" item you want.
Again, this is not an argument for or against any loot distribution system. I'm just saying that the game's writers might not be keen on affecting the game's storyline in such a manner.