Not always quite that simple Ozpaph. A true variety of a species is not just a different color. It would have one or more different morphological traits that distinguish it from the species form. A true variety also breeds true.All very interesting, and technical, but why would adding the 'forma' be important in awarding a species? Surely they are all 'just' colour variations of villosums and should be collectively compared as they are a single species.
Most importantly, in my opinion, is the fact that there are many plants that were once classified as a variety of a species that have since been elevated to species level themselves. If we don’t keep them separate by name they get bred together as if they were the same and we end up with a bunch of offspring that are not what we think they are. It makes a real mess for those who are trying to breed/collect true species or hybrids. Use Paphiopedilum malipoense as an example. At one time we had Paphiopedilum malipoense and Paphiopedilum malipoense var. jackii. If someone had bred them together in the past would they have been considered Paphiopedilum malipoense? How many crosses and back crosses between the two might have been made where the variety name might have been left off? How many ‘malipoense’ are out there that may not be pure? Paphiopedilum malipoense var. jackii has since been elevated to species level and is now considered a separate species... Paphiopedilum jackii. Today if you cross Paphiopedilum malipoense and Paphiopedilum jackii you get the primary hybrid named Paphiopedilum Marie Ponse.
The cross (Paphiopedilum malipoense x Paphiopedilum Valerie Tonkin) is registered as Paphiopedilum Hsinying Po Tree but the cross between (Paphiopedilum jackii x Valerie Tonkin) is Paphiopedilum Dragon Charm. Might there be some plants labeled as Paphiopedilum Hsinying Po Tree that are actually (Paphiopedilum Marie Ponse x Paphiopedilum Valerie Tonkin) and therefore not Paphiopedilum Hsinying Po Tree?
The short story is if we keep everything labeled correctly and keep good records we can always make corrections later if we need to.
Other examples might be:
adductum and anitum
concolor and josianae
barbigerum and coccineum