Mastery is particularly atrocious for unholy DKs. Essentially the worst stat we can have for DPS, aside from agility. Crit is also pretty bad.
My point is, the crit gems are going to be worthless and the gems that we do get to use are going to be boring and a step down from what we're used to at best.
Well if you want to run around with no meta because the concept of using one with crit or mastery makes you ill to look at, be my guest. I suspect most players will just math it out and use whichever one gives them the best damage.
I agree that the meta change is a bit overkill and I'd like to see the requirements reduced to something more reasonable, but I see no reason to overstate the case and make it sound like the other metas don't even exist or would not give any dps at all.