My son asked for a ramp wall after experiencing an obstacle course at VBS. We had talked about a climbing wall last year, and I was motivated to get building.
A CNC router is just cool. That's pretty much my basis for wanting to build one, though it is very versatile. It can cut signs and even 3d objects with amazing precision. Designing it has been a lot of fun as I've calculated weight, deflection, and center of gravity.