Actually, the rare bikes affected, seem to those with a *loaded* top box, *and* the stock rear suspension. The issues started with some police bikes in Europe, which usually carry lots of equipment. I have never read a story of the wobble on a bike with an upgraded rear spring or shock.
The rear spring that comes with many bikes (including my ST1100 and R1200GS) are too soft for most riders. An industry standard "person" is 170 lbs, which is a number from long ago, and is intended to average men and women. For example, the FAA uses that number as a standard person for aircraft weight (smarter pilots use a larger number!).
Most of the world's male people are heavier than 170 lbs, especially those here in the US!