Would they be missed?:
For a start, researchers do not know how many viruses even exist. Thousands have been formally classified, but millions may be out there. “We’ve discovered only a small fraction because people haven’t looked much,” says Marilyn Roossinck, a virus ecologist at Penn State University. “It’s just bias – the science has always been about the pathogens.”Rachel Nuwer, “What if all viruses disappeared?” at BBC
We really do not know anything like what we should know about viruses before we just shut down our economies in a panic and so forth.