When it comes right down to it, whether you cared for the writing or not, whether you loved Robert Pattinson or Kirsten Stewart or not, you cannot argue that the Twilight movie introduced a whole new generation to the beautiful vampire.
The first thing that you need to keep in mind is that this is not a new trope at all. Dracula was considered nearly pornographic when the first novel was introduced, and since then, movies like Lost Boys and Interview With the Vampire have continued the trend. The ability to live forever without growing old or sick is an intriguing and attractive concept, and with vampires who prefer to feed off animals instead of humans, it is even relatively moral!
What Twilight did was spawn a great deal of new interest in this familiar trope. It is very likely that Twilight had a lot to do with the inception of the popular television series The Vampire Diaries, for example, and it has introduced an entire new generation of book lovers and film fans to learn more about a new interpretation of these fantastic monsters.
Twilight also had the benefit of creating its own mythology, something that many works take on, and it deserves credit for its place in modern vampire lore.