Progress in genome sequencing technologies has transfigured biological research, including the field of virology. This had the unintended consequence of relegating structural phenotypic evaluations of viruses, and the associated methods, to mere complements of genomic approaches. Building on the work of Mazzone, and in light of recent advances in structural characterization techniques, we argue that individual virus molecular masses are distinctive characteristics that should be revisited. Based on available data, we estimated the theoretical masses of human respiratory viruses and observed that they distribute non-contiguously over a broad mass range. Our findings suggest that the total virion mass may constitute a meaningful attribute for a “phylobaric” (from ancient Greek ‘phûlon’ = lineage and ‘baros’ = weight) classification of human respiratory viruses. This observation could have fundamental implications in virology and relevance to public health.