I don't sail a Tornado so what do I know. But a couple of observations.
At the highest level, the inconsistency of one aluminum mast vs another is absolutely critical. Top Tornado sailors (and sailors in other Olympic classes w/ aluminum masts) talk about "finding" their mast 1 year ahead of the Olympics. And then they have to waste countless hours / days / weeks / months of valuable practice time learning to sail with their back-ups in case the break the first one. A mast can be the difference between winning and losing. At this level repeatability matters, and carbon is nearly perfectly repeatable.
Bill -- of course all sailors don't know how to specify layups, but that is a ridiculous argument. Sailmakers and sailors specify the flex characteristics and the engineers do the layups.
I don't know if the change is good for the class or not. I am sure there are trade-offs, but lets recognize valid arguments on both sides.