Structural and layout limitations, the extent of mechanical/electrical/plumbing replacement, foundation and site constraints, major additions or second stories, ceiling-height and opening goals, HOA or municipal review, uncertainty hidden inside an older home, timing, neighborhood value context, design goals, and any existing character genuinely worth preserving.
When most of those forces point in the same direction, the early planning path becomes clearer. When they conflict, a property review is more valuable than a generic rule.