I think VW is probably asking people to confirm because of the number of people who were backing out last minute. People seem to be putting deposits on multiple EV's at multiple dealerships, then just taking the one that comes first and cancelling all the other orders (e.g. Martin above). So it's not really fair to the people that have reserved months (or a year+) ago that those cancellations will then go to some person on a dealer's waiting list (who may have been waiting only a few weeks).
Even if 20-30% do not confirm, that will potentially move your spot in line up quite a few places.
For the record, I waited about 10.5 months for my eGolf, from online reservation to delivery. Given that VW has said the eGolf is essentially sold out worldwide, anyone who hasn't ordered will likely be waiting a long time.