There were a lot of complaints when the Night Revels' new 'expiring ingredients' mechanic was introduced with the new event last year. Well, I've finally ran some of the numbers and for casual players, such as myself, the results do not look good. You can see my results here (shameless, self-plug there).
Even though one of the reasons stated was to "encourage" running of the content, from my perspective, it is actually a discouragement. Since the non-chocolates are BtA anyway, why add the additional burden of having them "expire"? It never made sense to me.
Makes me feel like all of my effort this year will be wasted, simply because I do not have the time required to get some of the higher level items; I work for a living.