You are right! An automatic is probably a more convenient choice for 0-60. However, most people, including myself, didn't buy an M5 for stoplight races... some of us enjoy blipping the throttle while downshifting into a corner. Also, there is another section of this site for discussion of similar cars.
Sorry but I really hope BMW never put an automatic gearbox in an M5. That would be the last nail in the coffin of what has become less of a drivers car since its launch. Don't get me wrong I really love my E39 M5 but if they add any more drivers aids even my grannie would be able to drive it!!!! If you want an auto then get an Audi S8, MB E55 or Jaguar XJR and if you want to go faster than anyone else 0-60 get a superbike.