Hi @Helvetosaur,
The solution proposed by you and @Piotr changes the behaviour for new objects. You also need to select all the pre-existing bricks and change their properties to turn off their isocurve display. To get the isocurves to display again you have to select the objects and turn them back on.
Where you want the change to be universally applied, but not necessarily in all display modes I prefer to change the display mode settings.
