Because it needed to be done.
As many an anime-styled fanartist has discovered to their chagrin, Light Yagami from Death Note and Edward Cullen from Twilight look remarkably alike. But their similarities aren't just in appearance. ;]
I highly recommend both series to everyone, but for totally different reasons. Death Note is a brilliant psychological thriller that explores the nature of evil, while Twilight is likely the most romantic story that has ever been written. (So what are you in the mood for today?)
Edward is really nothing like Light (he having matured past his teenage god-modding stage 80 years ago), but the similarities to his past are enough that Death Note would make Edward extremely uncomfortable. L-like Alice is totally just for the lulz.
Edward and posse from the Twilight
Saga novels by Stephenie Meyer.
Light Yagami and Ryuk from the Death Note
manga and anime by Ohba and Obata.