To me this only makes sense that the consumer know exactly how old their NV Champagne really is. What if a person buys a bottle of Veuve or Moet at the Cost co. that has been sitting around for a few years??
Is an aged bottle of non-vintage cuvée going to taste consistent to the house-style if it is several years old?
Who really knows how long those wines have been warehoused and what conditions they have been stored in. To me it would only make sense for the producer to supply the disgorgement date on the bottle for quality control issues as a courtesy to the consumer.
Can you imagine if all perishable products didn't carry expiration dates on them?
Here is a list of Champagne producers who print the disgorgement date on the bottle for their NV wines. Courtesy of Bruce Sanderson of Wine Spectator:
Charles Heidsieck
Jacquesson
Bruno Paillard
Grower Champagnes: Jean Lallement, L. Aubry, Gaston Chiquet, Pierre Gimonnet, Rene Geoffroy, Mark Hebrart, Chartonge-Taillet, Varnier-Fanniere, Margaine, Henri Goutorbe, Jean Milan, Henri Billiot, and Vilmart.