SMART's policy is, IMHO, a good one. At $99/reservation, there would otherwise have been very little ability to stop someone from reserving 100 or more cars ($10,000 investment, not all that much) and then selling those reservations on e-bay or craigslist (or however) for a significant premium. That would then create a significant secondary market, essentially, raising the price of the car -- and destroying the market niche/presence of the SMART as an affordable vehicle. People would be forced to either pay the premium (which, given the demand, could be several thousands of dollars) or to suffer an even greater delay in delivery as the scalper's cars are manufactured and imported.
I do agree, however, that you should be able to assign your reservation to a family member.