I'm not contradicting the ideas expressed in this thread--they are all well and true--but I actually am disappointed that Blizzard went with this decision. It was certainly not a surprise but I had hoped they might change their mind. I thought they might hellforge (say) the artifacts instead, transforming them to something new while preserving what was nice about the system: namely new powers every expansion. I admit the one weapon per spec was highly problematic but they could have solved that by making all artifacts level together or something similar.
They went another way and I think it's something of a pity. The neck in no way excites me as much as the artifact weapons did--it's basically the ring all over (yawn)--and they really, really, REALLY needed a method of temporarily adding powers and abilities to specs that will be gone the next expac. Or, of course, might become permanent at the expense of another old ability.
And artifacts could have done that.