Alternatively, although it's really in addition to, of course emmisssions plays a role, but I dont think that alone is the reason. It's an easier job for the engine management folks to deal with the slower temp changes as buffered by liquid cooling.
Right now there is only one the GS all the other twin oilheads are still air/oil cooled. Think thi is purely performance HP. Power produces heat, I think BMW hit the wall in HP with the twin about two years ago with the HP models..
They also went to a wet clutch.
110 HP to 125.. wet slipper clutch..
And I believe the coolant is measured in ounces not quarts. Less than one quart.
I'm intersted to see how it does. Engine/transmission actually got smaller with the addition of coolant and the wet clutch.