Welcome changing requirements, even late in development. Agile processes harness change for the customer's competitive advantage.
As discussed, the cost of change is much higher in hardware development due to the Hardware Effect. As we may welcome changing requirements, we must balance this change with the cost of delaying our project launch.
In both software and hardware, the requirements changes referred to in Principle 2 almost always increase Sales Volume or Sales Price. And they almost always increase expenses. They may or may not cause a launch delay. In hardware product development, they often increase our unit cost (COGS). The difference between hardware and software appears in the launch delay and unit cost factors.
In summary, the time between ‘design’ and ‘test’ in hardware is larger. This makes the delay we incur with hardware changes larger, which increases the cost and reduces the economic value of a change. As a result, fewer of the changes we would like to make turn out to be profitable.