It's the rider's attitude that makes them unsafe.
As far as cost, it's relative. You can buy one of these sportbikes, such as the new Yamaha R6 with some 130HP engine, with all the latest and most sophisticated racing techonolgy installed, for 10 grand. If you were to try to buy an automobile with equivalent amount of race tuned components and performance, it would cost over 100 grand! Actually you probably couldn't legally drive such a race bred automobile on the street!
Actually the stats give the safety nod to the land barges like the Goldwing or ElectraGlide Ultraclassic. At the end of the day, the greater visibility of one of those is more apt to save your ass than all the horsepower in the world.