Variable wattage has to do with consistency of the output. Regardless of the ohm, it will give you the desired heat across the board, irrelevant of what you put on top..that is the true benefit.
Have to chime in on something, VW is not a set and forget. While the wattage may be consistent, there is a difference between using say a 1.5 ohm dc and a 2.0 ohm sc carto. The same wattage the juice shines in the dc, scorches the juice in the sc carto. VV and VW both require adjustments depending on what exactly you're using....
I think what we really need is a constant temperature device with a control to set the desired temperature...