Logically if you keep going from the taxiway you already have the taxi speed to benefit your takeoff roll. There is also the ATC clearance of 'cleared immediate takeoff' which would encourage this.
However there are a couple of reasons why a pilot may not do so.
1. The ATC clearance 'line up and wait' would preclude it.
2. Before setting take of thrust you 'stand up' the throttles / thrust levers to ensure both engines spool up - gas turbines are notorious at being slow to spool up. Then you increase the thrust to takeoff thrust. This ensures both engines increase to take off thrust at the same time. Doing this after a sharp turn on to the runway ensures you are not taxiing down the runway while the engines spool up (runway behind you being one of the useless items).