We are all used to plugging USB devices into our laptops and desktop machines. If you are working in a VMware Horizon View environment, you might want to continue using your USB devices within that virtualized desktop. USB device redirection is a functionality, built into Horizon View, that allows the USB device to be physically connected to the endpoint device while working as if it's connected to the virtualized desktop.
On the flip side, you might want to prevent users from plugging devices into their virtual desktop machines, to ensure you have a secure environment. After all, deploying a VDI environment is one reason companies use to create a secure environment and protect data.