Long shank type prevents troubles for overhang application.
Have you had any troubles using a long straight drill when long overall length is demanded for preventing collision with workpiece?
Shorter flute length in comparison with conventional long straight drill is used to maintain high rigidity, thereby preventing various troubles.
Better engaging stability since the thinning part whose point angle is obtuse becomes smaller.
Lower cutting force since length of cutting edges formed by thinning becomes shorter.
Better chip disposability because the core dia. can be smaller and the chip pocket becomes bigger.