With even a simple flight plan, actually flying an aircraft is considerably easier than if no flight plan at all is prepared. In the real world, one would add "and much safer", and under IFR, a flight plan is mandatory. The flight plan being discussed here is the flight plan for the pilot, and may be alternatively called the "Pilot's Log". The flight plan required for VATSIM is for the benefit of the Air Traffic Controller. They are slightly different, but the VATSIM flight plan is simpler and can be quickly generated from the Pilot's flight plan using the built in Flight Plan forms included with Squawkbox and FSInn.