Best Practice #5 : Enable Network I/O Control
distributed switch traffic is divided into the following predefined network resource pools: Fault Tolerance traffic, iSCSI traffic, vMotion traffic, management traffic, vSphereReplication (VR) traffic, NFS traffic, and virtual machine traffic.
— vSphere 5.5 Networking Guide
And it is likewise very helpful for the "noisy neighbor" scenario, this time applying to network traffic—which if it is IP-based, can still apply to storage! Touché!
Or perhaps you have an extensive test and development division. And you are consistently testing apps, but you don't want them to affect your production network traffic. A good NetIOC design can seriously help with that.
And if you want to get really serious, you can check out Frank Denneman's article on designing NetIOC for consistent vMotions across multiple NIC architectures.