When you Virtualize your servers they become a handful of files. Backups, upgrades, patching are no longer wrought with worry. You can even move your virtual computers to the cloud and run your infrastructure from there.
I can't think of anything bad about virtualizing your servers, or your workstations for that matter. Imagine your work computer being a handful of files on a removeable drive.
And virtualize you work computer while your at it. Imagine having your work computer stored on a small usb drive on your keyring safe and encrypted in case somebody stole it or you lost it.
The same computer you use at work you could use at home.