Issue:
How to simplify polylines with a large number of vertices in AutoCAD. In the example below, the object on the right contains a large number of vertices, while the one on the left has fewer while maintaining the same shape.
Solution:
Currently, there is no dedicated command in AutoCAD or AutoCAD LT to simplify such complex polylines. On AutoCAD Map 3D and Civil 3D, a dedicated function is available. See: About Weed Polylines.
Note: The process is called weeding and there are several custom LISPs which may be used in AutoCAD to achieve this.