Apart from being able to hide from the OS a hypervisor is also safe from manipulation by the OS and can observe and manipulate anything the OS does. This opens

Apart from being able to hide from the OS a hypervisor is also safe from manipulation by the OS and can observe and manipulate anything the OS does. This opens a few doors: debugging or reverse engineering the OS or kernel modules, sandboxing a system you don't trust, detecting rootkits, protecting your antivirus solution from malware, etc.