It's a calculated, higher-level marketing decision. This is Lange's first regular-production steel watch. Lange knows that steel watches made by other high-end brands command a premium, and so Lange is just trying to capitalize on that current phenomenon by saying, "At least initially, these steel pieces will go to our existing customers." I think it makes sense for Lange to do this initially, and then to relax this "requirement" later on, once demand among existing customers is satisfied. I think they're specifically focusing on existing customers who made recent purchases, too -- not folks who bought a Lange 1 20 years ago and probably won't be getting anything else anytime soon.