When poet William Blake wrote of "dark satanic mills", he couldn't have been looking at a steel mill because there were none in 1804. Nevertheless, when I visit a steel mill, Blake's phrase always comes to mind. With the heat and the pounding noise, the dust and smoke, and the red glow against the night sky, it's hard not to see these places as infernal. And yet the process of making steel also produces some of the most hauntingly beautiful images found anywhere in the world of industry.
In software development deadlines are a necessary evil. It is important to understand when they are necessary, and it is important to understand why they are evil.
Estimation: When estimating engineering work a substantial time investment is required by an engineer in order to get an accurate estimate.
Misaligned Incentives: There is an incentive to lie and give estimates much longer than the feature is truly expected to take.
Low Morale: Deadlines are likely to be missed often. Repeated failure has a cost to the morale of the team.
Micromanagement: Deadlines are wielded by middle managers as a whip to harass and annoy engineers working on features.
High Stress: When engineers feel the pressure of other stakeholders holding deadlines over their heads it creates an environment of high stress.
High Turnover: On teams with high turnover rates the best engineers have an easy time finding new work and leave quickly, the worst engineers have a difficult time finding work and remain. This selects for a lower quality team over time.
The resolution is simple. Never have internal deadlines. Operate on a prioritized and ordered list of features. Estimate only when necessary to prioritize and do so in a t-shirt sizing way. Trust your engineers and they will begin to love their work. Engineers who love their work are happy and productive.