“… software economics has often been misconceived as the means of estimating the cost of programming projects. But economics is primarily a science of choice, and software economics should provide methods and models for analyzing the choices that software projects must make” - Taming the Tiger: Software Engineering and Software Economics, Leon Levy
The estimates are needed to make those decisions. This is the basis of the Microeconomics of decision making in the presence of uncertainty. These estimates support all 5 Immutable Principles of Project Success.
