Poor Traceability can cause you much

1. The development team cannot prioritize the modules based on the importance/priority. Ultimately leading to the misinterpretation of functionality flow
2. The project management will also be affected since there will be long time plan due to the lack of clear idea about the interfaces.
3. Testing is compromised as the coverage is not verified at every stage of the life cycle.
4. In the case of delivery team it is really hard for them to declare that the product is ready to be demonstrated.
5. Finally maintenance becomes really tedious as identification and analysis of the impacted work products and requirements becomes tedious