The Model Statistics pages provide statistics for the objects in PA / TM1. The snapshots are very useful for establishing baselines before making changes or troubleshooting performance issues.
The cubes page for example allows you to see how much memory that each cube takes up and assess the ratio of populated to fed cells. These stats help to identify problem areas, bottlenecks and performance degradation over time.
The dimension stats page allows you to identify large and complex dimensions with lots of levels. It can be used to highlight which dimensions require maintenance work.
The process and chores pages allow you to assess which objects have been executed daily or in between documentation runs.