I have had a 97 Kilauea since 1998 and I have no marks from the cable crossing the downtube.
Prior to 1997, Kona produced bikes with both cables going down the down tube and I always route the cables so that they cross as they go down the down tube. You no doubt think I'm mad?
Maybe you're right. But I have bought many Konas, and other bikes, that have really unsightly damage on the head tube, with large areas of paint rubbed off. This is caused by owners routing the rear mech cable down the right hand side of the dt, so that the cable rubs on the head tube. Matched by the damage of the other side by routing the fm cable down the left side. I route the rear mech cable down the left so that the curvature of the outer carries it away from the head tube and it never touches the head tube.
Consequently my 97 Kilauea has no unsightly damage to the head tube. Nor does it have any on the down tube. Doesn't prove that I'm not mad of course, but I think it is evidence that Kona did the right thing.