[chmod]

There's a lot that can be done with a compromised system for one it's an an anchor point into into the network meaning it can be used to locate and attack other systems, bypassing the router's firewall as it comes from inside the network and therefore trusted. There's also the ability to upload or download files view and modify configuration files you could also add it to a botnet or whatever else you want a rooted machine becomes your machine in a a sense.