DE roll is actually the main reason that the green essences are worth more than blue shards. Which is actually against blizzard's own logic.
Rubbish excuses like "but you needed the whole group to get there" do not count, because neither miners nor literally people with any other existing profession can get their ores or whatever they're gathering in the dungeons without the effort of their groups. I've even had rogues that refused to open one lockbox. Or PuGs in DS that looted a BS Plan and then refused to craft it for me for free.
I think blizzard should actually at least somehow add an option in "need for greed" mode, if the enchanter in the group is willing to share their ability to disenchant items with the other puggers. I'm sure most people are generous enough, but to be forced to do so as it is, I'm just feeling a little bit uncomfortable.
Edit: Some people can't see the simple fact that without the DE rolls, shards would cost much much more than just vendor price of a blue, simple because there would be so much less of then on the market. So even if the enchanter still only gets the same amount of shards in 5 man pugs, he's actually getting more than the rest, because he can disenchant. As it is right now, I can actually roll need on everything I can in 5 man PuGs, because having a 100% or even a 50% chance to loot something and vendoring it, is going to end up more profitable than sitting on a 20% chance for a shard, which is also worth 20G. So yes, it's broken, and needs a fix. Don't think blizzard wants to encourage these kind of things.