Using Hardware and Application consolidation results in cost savings through reduced power and maintenance of the server cost and buying fewer licences of software. Hense you can think of using virtualiation and consolidation to reduce your data center bill or your server farm cost of operating.
New investment in Hardware or software should be done taking into consideration all these factors as the new blade and rack servers are very high on computing power and power efficiency and hense all these factors can very easily contribute towards reducing the Total Cost of Operation and Maintenence. Also the architecture results in reduced real estate requirements which is so very much crucial in running the operations in a Real Estate costly ( Read Cosmopolitan ) environment.
Also simplicity in the data Center also results in ease with which scaling can be done by taking into account the upgradibility of processor accomodated by your motherboard. Backup and restoration is also simplified.
But one point is that high availability would be required as if one node fails multiple applications can go down, hense increasing the criticality of the Appllications stored on these architetures.