Because he's ultimate, the dream Super-Villain of all times!
I think DC themselves aren't aware of what they have created, a Master of all! Ra's Al Ghul is definitely a character that needs its own movie. He is dark, mysterious, dangerous and over all, a one man army!
I would beg for a Ra's Al Ghul movie. After I read the 'Birth of a Demon' series, there was only one question in my mind, why aren't they working on this? When Dennis O'Neil and artist Neal Adams created him, they didn't know how it would conquer the fans's hearts and rule over their minds, and so DC, if anyone of you are reading this, think about doing this!
Here is my dream cast and crew for a movie named 'Demon's Head' or simply 'Ra's'!
1) Director: Sir Peter Jackson or Zack Snyder/Christopher Nolan
It's difficult for me to choose between The Dark Knight, Man of Steel and The Hobbit. The Ra's Al Ghul's Story is slightly about Arab and all War-Talks, so Zack Snyder can think of that. Peter Jackson has his way with costumes it needs and Christopher Nolan is our Dark Warrior, thus making it difficult to choose! Vote, maybe?
Director for Ra's Al Ghul's?
2) Ra's Al Ghul: Jason Isaacs/George Clooney/Hugh Jackman
The lead, the nightmare, the demon. Another difficult one to choose!
Cast for Ra's Al Ghul?
3) Batman (Bruce Wayne): Michael Fassbender
It's like he's born to be the Dark Knight. There is no other person on the earth fit for the role. I mean, look at the physique, the look! He's born for Bats, not Magneto!
4) Talia's Al Ghul: Aishwarya Rai Bachchan
There could be many other actresses fit for the role, but the image of Talia's Al Ghul is perfect as for her's.
5) Damian Wayne: Logan Lerman
I was thinking of Robin when this boy caught my attention.
6) Nyssa: Michelle Rodriguez
Yea, she's active, she's sporty, she's extremely hot. Plus we saw her in Fast and Furious, isn't she perfect?
7) Selina Kyle (Cat-woman): Kaley Cuoco Sweeting
Just imagine this Big Bang Theory actrice as Cat!
8) Nightwing (Dick Grayson): Ian Somerhalder
I swear, he was the first one who came to my mind!
9) Alfred Pennyworth: Hugh Laurie
Yes, i think he'll carry out very well. I thought of Alan Rickman, Michael Gambon and John Wesley Shipp too.
I just wish DC gives a little attention to this Freaky Awesome Desire of us all. Ra's Al Ghul is a man with many fans. Please!