Most networks have now been in existance for almost 30 years, and while much has changed in that time, it's very common for systems, protocols, operating systems, and applications from the past to remain on the network longer than they should. These legacy elements represent weak points in the IT Security profile so locating and eliminating them should be a priority.
The effect of good Cyber Hygiene is multi-facteded and far reaching implications. These include better results in Risk and Vulnerability Assessments, reduced exposure to attacks, reduction in the cost to manage the system, and reduced ongoing maintenance costs for software and systems that are no longer used, but still under maintenance contracts.
In addition, event volume is a challenge in most IT Security organizations. Reducing the noise created by legacy and outdated systems, software, and applications improves the quality and the relevance of the security events stream and allows for a more efficient, productive organization.