In the best cases much can be assumed about the biology of the virus. Even in the worse case a framework for investigation would be suggested. Because there are so few virus discoveries now being made which do not fit into the existing classification scheme we can state with a degree of confidence that most of the major groupings of viruses infecting humans and domesticated animals have been identified. So classification is useful. At the moment classification is really only important from the level of families down.
All families have the suffix viridaee.
Genera have the suffix virus. There is an element of subjectivity about it. HIV-1 has many different strains with different properties, some infect brain cells, others infect macrophage cells. Such variation is extreme but is a feature of viruses with an RNA genome. Basis of Taxonomic Classification.