I_Write_Ivre
It's not like that's new for vampires or myths. No one cared two hundred years ago and no one cares now.
This hits it on the head exactly.
Myths are changed constantly, both because of shifting views and the fact they vary amongst people at their base. Trying to find a concrete myth is like trying to find a perfectly explained urban legend; you can't. It picks up pieces here and there in retellings, localizations, so on. One thing that comes to mind is
Theseus and the Minotaur, who in some legends stabs the beast but in others actually has to pierce it with its own horn to break through its tough leathery hide. That is a very large difference, in my mind. Additionally, there are interpretations where the Minotaur is closer to a centaur in appearance, and this is something that was never necessarily dispelled.
Additionally, no one blinked when Suzanne Collins used the
Theseus myth as the basis behind her
Hunger Games. Myths speak to core values and nature; the finer details aren't quite as important.
A lot of people tend to compare Meyer's vampires negatively to Bram Stoker's, saying that she has 'warped' the source material or what have you. What those people fail to realize is that Bram Stoker was just as ruthless, if not moreso, with his own interpretation of vampires.
That said, I am a bit of a d**k about how certain myths go and tend to get peeved when (what I feel are) important aspects are altered or changed. Take the recent depiction of the Greek Pantheon in modern blockbusters.
As others have said, if you can come from the original place and appreciate why things were a certain way, I guess you can pull it off. It goes back to breaking rules; so long as you know why they are there, you know when it's appropriate to break them.