There are some well accepted and inherit benefits to using Virtualization. Here are some of them:

Reduce the number of physical servers
Reduce the infrastructure needed for your data center (power, cooling, battery backup, network switch ports, KVM ports and space)
Reduce administrative overhead because servers can be administered from a single console
Ability to bring up new servers quickly (it could take days or weeks to put in a new physical server but it could take just a few minutes to create a new virtual server from a template)
Hardware Independence of virtual servers – a virtual server can run on any host server, regardless of the host hardware
Because of hardware independence, you receive reduce your disaster recovery cost, complexity, and recovery time
A “greener” datacenter & server environment due to the consolidation
Overall, lower TCO of servers