Haywood:

Some ARF manufacturers recommend low powered engines as a way to avoid product liability claims. The airplanes will fly in a scale manner with the recommended engines, but anyone looking for more performance will use a bigger engine, which not only voids the warrenty, but gives the manufacturer/distributor/dealer a strong defense in any subsequent liability lawsuit.

Knowing this, the better manufacturers will design the airplane to balance with the heaviest recommended engine. Therefore, a light engine will require nose weight.

World models and EZ take this philosophy to an extreme.

Jim