Why does not the X-E1 have the 1/2000 synchronized shutter speed for flash like the X100 ?

Flash syncro at very high speeds  only works  with leaf shutter cameras. If you want this option you will have to go with the x100, Sigma DP series or Leica X series which have fixed lens leaf shutters. All other camera's I believe have fixed flash syncro speed due to having focal plane shutters that don't work with variable flash syncro and that includes the Xpro1 and XE1.