> If this code was fully tested and maybe refactored (isolated) when the need arises, the cost of change would almost go to 0 because you would only have to imp

> If this code was fully tested and maybe refactored (isolated) when the need arises, the cost of change would almost go to 0 because you would only have to implement a new feature without touching the old code. You don't even know the "change", you just assume that it will be a change that takes zero effort to implement, to satisfy your argument.