How do you get enough space above the wall and below the roof for both massive insulation and ventilation? One way in new construction, or even in the rebuilding of a roof, is what we call a Raised Heel Truss. This design forces the overhang of the house further out from the house, but does give us the space to do both insulation and ventilation properly, something almost impossible with the old technique of sitting roof rafters right down on the wall.
A Dropped Ceiling Truss will force the wall up higher but give us this same "room to work" without extending the eves out more than on a traditional house.
New truss designs can also eliminate the common problem of Truss-Uplift by moving from a three sided triangle to a more complex geometry, which provides some flexibility in the truss, avoiding the forced lifting of the bottom cord.
The moral? Traditions brought over from days when energy was cheap and insulation was minimal are not always valid today, and there are a lot of new products and methods which allow us to do things right. A little research should allow you to match the "look" you want with the "efficiency" you need.