D'karr
Adventurer
In some cases, going back to the source wouldn't be a bad thing. But in some cases, the D&D monster is nothing like the original (such as the gorgon). In those cases, I hope they keep what the D&D creature has evolved into.
Not too long ago, I watched a Jason and the Argonauts mini-series. I believe Jason London played the titular Jason, but I can't recall - my argonauts all get muddled. In this mini-series there was a creature very reminiscent of the D&D gorgon, which Jason had to defeat as part of his tests.
It's been a very long time since I read the original myth, but I was pleasantly surprised to see the "gorgon."