Oh boy, don’t get me started… 
I definitely agree with and support all of the responses so far.
One plea I will make, regardless of “sourcing” of common names, is that folks avoid more-or-less literal translations of scientific names to be used as common names. If we call Cryptantha hoffmannii “Hoffmann’s cryptantha,” and then later the scientific name gets changed to Oreocarya hoffmannii, does the common name then become “Hoffmann’s oreocarya”? If yes, then it was never a common name to begin with. It was just a non-Latin scientific name. (I have reviewed too many technical manuscripts attempting to propose such things!) If it didn’t change, then maybe it really is a common name, though I would still question its presence in the common vernacular of any area.
A local botanist and early mentor of mine, Mary DeDecker (1909-2000), once wrote that the best common names are often those used by children. They tend to capture the imagination and are more likely to “stick” in vernacular usage. I couldn’t agree more. Common names are hugely important in the public-facing work that I do (and that iNaturalist does!), and names that stick and capture the imagination can only be to the good. So in the rare cases where I’ve felt compelled to “invent” a common name, I have tried to channel the inner child… (or have been fortunate to be in the presence of others who already had done so!)