Simulation is a useful training tool especially for complicated aircraft. The simulator can be used to demonstrate all manner of malfunctions and flying characteristics that cannot be done as easily or effectively in the real aircraft. For example, practice engine fires and engine failures in the real aircraft require instructors to either detail a long list of symptoms to the student or use some other method of indicating to the student that there is a problem. In a simulator the student gets all (almost) of the indications that would be in the real aircraft. However, simulation is not perfect.
Although a simulator may be classified Level D, zero flight time etc this can be a bit misleading. Level D really only applies for airline style 'fly the aircraft' training.
At present the jury is still out on standards for tactical simulation systems. Simulators cannot sustain G.
The point of all this is that a Level D simulator is still not enough for zero aircraft flight time training especially in the military environment. The point of the simulator is to enable the crew to operate the aircraft. The crew must go and do this in the aircraft and only be assisted by the simulator for currency and proficiency training. Organisations can either have smart people who realise this from the start or they can learn it the hard way.
PS I'd check the info on the German Tiger crews just to make sure the figure is not related to the lateness of their aircraft delivery. I'm pretty sure that they are not in a mature training environment just yet.