That's what I've been saying about this virtualization for security craze.
Existing operating systems already provide virtual environments to applications. There's no need for another one, just properly use what is already there! For example: run Firefox as a separate user account or use SELinux to isolate it.
I've also been saying that as more features are added to virtual machine environments, our systems are going to end up with the very same problems we already have. The VMware, qemu or VirtualBox virtual devices, networking and fancy control ports are going to have bugs. These bugs will end up being exploited and then you're right back in the same security situation that exists already.