Why developers detest estimation and forecasting?

To be able to work. Makers and artists, which software engineers are, enjoy working. They like being useful and spending time tinkering with whatever happens to be in their field of interest. What they typically don’t enjoy is to deal with something they cannot perceive to be real, valuable, and true. They markedly dislike the situations where they are the originator of things with questionable worth.

For makers, it is preferable to describe a complex problem in a complex way, rather than sacrifice the truth and provide simplistic and untrue answer. Makers can bend a little and deal with uncertainty, but only for short periods of time. They prefer to spend their time making things. 

Why is this important? Because it is important to understand that software developers detest estimation, and forecasting by extension, since they cannot be proven to be true. They are only a guess. And for makers a guess represents little value. For this reason, we need to be sensitive and empathetic to their dislike when we need their input and cooperation. When developers see that we understand the binary unsustainability of our own request, they will oddly be more willing to help. But it is also important for another reason—when developers see that our forecasting efforts are ultimately designed to provide them with a more sensible environment for work, there is a material improvement in the relationship’s dynamics.