Well I see it a little diff., Vlas and and Charley have been writing Death Note since 2008, before WB announced it,
Virtigo has some weird deal with WB
http://blog.newsarama.com/2008/06/03/screen-bites-61/
the date is 06/2008
in doing research i found excerpts from the script was leaked in may 09 on a french death note site
http://www.death-note.fr/home.php?page=news3
To be honest even if this script is fake i don't see the real script being a huge deviation from this
The leaked script is very conservative
a screenwriter once told me hollywood doesn't write movies for LA, NY, Chicago
they make movies for the biggest movie markets, which are conservative cities
St Louis, MO and Nashville, Tn
having ryuk and death note at once would be just to much for those people, this way they can focus more on the death note
maybe? for sequels ray pen. is still alive, so to avoid jail time luke kills ray when he finds a torn page, and ryuk comes because he likes lukes style and digs up the death not for him, so he can kill ray's girl ,
and L brings Luke on board because someone is claiming to be The 2nd Kira, Lukes motivation in the 2nd movie could be to avoid jail time and death
and the 3rd can be about building a perfect world,
you should know Roy Lee the Ceo of Virtigo Entertainment
he gained fame for turning japanese movies into u.s remakes, when asian companies wanted to just sell their movies in U.S as is, he told them they're too japanese to work, and they gave roy the rights to sell the remake to a U.S Studio