Hi Donald,
In this example, I only used the routers so that I would have some devices to ping with/to. I also could have used computers but routers are easier since you can access them through the CLI and you don’t have to worry about firewalls blocking ICMP traffic.
Sometimes, it can be useful to have a router in front of the ASA. As a firewall, the ASA does a great job at packet filtering / VPNs but it’s a poor router. If you want to use specific features (like policy based routing) then using a router in front of the ASA works very well. If you don’t need any router specific features, you might as well connect the ASA directly to your ISP.
Rene