They are probably making this a mandatory purchase because the cars are starting to get older. A new volt would have little use for these things, but as they rack up miles and abuse, the time will come to start servicing them. And as lack luster as sales have been to this point, they do not need horror stories form dealer service to give them another mountain to climb.
It is a new technology and requires new tooling, technicians to handle it. That costs money. Not sure what the dealers are so surprised about. I bet they jumped at the chance to carry the volt thinking it was going to fly off the lots. But selling 5 in 2 years, is comical at best. The Volt makes sense to certain people in certain areas of the country. Perhaps this part of the country does not have the market to support the Volt. That happens.