Price is a factor
Agility is important yes but actually price was also a factor in our moving to the cloud for our comany websites. By moving from a traditional managed datacenter to Rackspace Cloud Servers we saved about 1/3 of our monthly costs. Ok so we have to manage the cloud servers ourselves but having managed servers just meant we were spending a similar amount of time filing support tickets, resonding to emails and sitting around waiting for the datacenter guys to do the work. So we really have saved money by going cloud.