Good point. Virtualization has many benefits: easy migration, lab testing, flexible in hardware resource, not so dependent on hardware-age

My mayor gripe with virtualization is the licensing model some software vendors use. If you have more than x cores than you need our super expensive license.

If you buy a modern cpu with 6 cores you need to pay license fee for all of then, doesn't matter if the virtual machine with the software on only uses 2. If you run it in a failovercluster you have to pay twice(2*6) as the cluster is viewed as one whole.

A minor is the added complexity of resource usage/influence tracking.