Bringing an old house up to date energy-wise can improve comfort and energy performance. Adding continuous insulation over the exterior walls and roof makes a continuous thermal barrier while burning your thermal bridges.
It makes sense when replacing the siding or roofing because it is a once-in-a-lifetime opportunity.
Wrapping a house with insulation can cause headaches if not done thoughtfully: make sure that the air, water, and thermal barriers work together, not against each other, because trapping moisture in a tight house means #BugsMoldRot.