We need them to simulate good judgment at certain critical times. We instinctively use lists for survival. In a development situation, you or I might choose not to do some task in a standard because it might not be appropriate for the project or organization. In many modern standards, the only mandatory activity is tailoring the standard to your particular needs. Modern process standards are not designed to replace professional skill or experience in software development.
Pilots know how to fly before they are hired by airlines.
The value of putting the tasks in a standard is it forces standard users to at least acknowledge, and better yet, to attempt to understand the possible negative consequences of not doing the tasks in the standard on their projects. This is the heart of the tailoring process. It is a critical part of successful project planning. The earlier standards did not reflect current thinking that process standards can be standard checklists. It does not seem sensible to many people to completely ignore these insights and start a list from scratch based only on personal, necessarily more-limited experiences.