Because there have been no...
Because there have been no studies of motorcycle crashes, we don't know if there errors of other drivers, as in this case where the driver fell asleep, are a rising factor or if motorcycles make more errors that kill themselves.
Preliminary fatality figures released by the National Highway Traffic Safety Administration (NHTSA) indicate that motorcycling fatalities rose by by 11% in 2003. According to the NHTSA release, the number of motorcycling deaths on U.S. highways rose by 348 to 3,592, continuing a trend that has lasted since 1998, when motorcycle fatality numbers first turned up after a decade-long decline.
The overall traffic picture was mixed, with total traffic fatals up slightly (by 405 to 43220 or .9%) but total recorded injuries in highway accidents down (by 1.2% to 2,891,000). Most other vehicle categories were down in fatality numbers, but SUVs, which have had an even greater rise in popularity than motorcycles, showed a bigger increase in total fatality numbers than motorcycles, with 456 more deaths than 2002 (from 3995 to 4451). Comparing the total numbers also reflects motorcycling's terrible fatality rate (that is, fatalities per mile traveled), since Americans travel many times the mileage in SUVs that they do on motorcycles.
The preliminary NHTSA report shows motorcyclist injures down from 65,000 to 64,000, though we don't know how reliable this figure is. If it is accurate, it either means that motorcyclists are crashing less frequently or are sustaining fewer injuries in crashes. Either way, fatalities appear to be increasing on a per-crash basis, which might reflect a reduction in helmet laws and helmet use.
However, such reports continue to generate more questions than answers. The bottom line is that no one knows what more motorcyclists are dying because there is no useful recent research into the matter. A current transportation bill working its way through Congress contains authorization for a crash-causation study on the scale of the quarter-century-old Hurt Report, and such a study could provide some useful answers and show us how to reverse the trend. The American Motorcyclist Association has renewed its call for such a study following the release of these latest fatality numbers.
The full preliminary report is available on the NHTSA site (this is a large, slow-loading pdf).