In this blog post, By Scott Sehlhorst starts with a simple fact: if there is a lot of discussions on how to write requirements, there is not so much material on why to write requirements. His advice is that you should start by thinking about why you write requirements before you decide how to write your requirements.
Scott Sehlhorst provides the following reasons to write requirements
* Improve your understanding of what your market needs (from you).
* Decide on the sequence in which you will deliver what you choose to build.
* Collaborate with (and set expectations for) your engineering team.
* Manage expectations with your stakeholders.
* Improve the efficiency of your product-creation process.
* Remember why your team created what they created.
Each of these reasons is detailled in the post. The conclusion is that we should “keep in mind why we write requirements. When considering how you will write requirements, think about the impact of different techniques on the goals that matter to you.”
Read the complete blog post on http://tynerblain.com/blog/2013/07/17/why-write-requirements/