Fictional vampire “rules” change constantly and you’d be surprised how recently some of them were invented. Almost nothing that people associate with “vampires” has anything to do with real “vampire myth,” that is, folklore beliefs. That’s especially true for the idea that vampires are harmed or inhibited in any way by sunlight, which is a 20th century movie invention. Writers are free to choose any “rules” they want as long as they apply those rules consistently. Readers have different preferences, one reader’s sancrosanct rule is another’s stale cliche. But anyone who thinks vampires are “supposed to be” done in a certain way or that the Twilight Saga “changed vampires” in some way has a very narrow view of the field.