I sometimes wonder whether, when the original grading guidelines for oak were established, a double meaning was implied by the term "common grade" based upon its frequent use in floor installations. For that matter, is it coincidence that most of the woods utilized for flooring -- and throughout the construction industry as well -- are "plain" sawn and go by simple, one-syllable names such as oak, pine, ash, and birch? I guess it's something to ponder.
During the past decade, however, exotic hardwoods have become more "common" in wood flooring products. Early on, dealers/contractors showed interest in exotic species but, at the same time, they were reluctant to embrace them in flooring products.