It is all about instantaneous switch.
I manage about a hundred computers and serve as point of contact for all technical questions about them. It is very useful to be able to connect to any of the computer I wish using single keystroke. In these 10+ years I remember placement of every computer by heart and usually don't spend more than a second to switch to the virtual desktop. In rare cases when a terminal to a computer is closed (computer rebooted or network problems), my setup automatically starts new terminal according to the particular workspace setup.
Besides connectivity to the computers, there are ongoing projects with many windows open. It saves lots of time to have all task-related windows in single workspace and be able to switch between tasks without having to set up work environment anew.
