Joss Whedon Will Direct, Write and Produce DC's Upcoming "Batgirl"

According to Variety it seems like Joss Whedon is going to get his wish of directing a film set in the Bat-verse. Reports indicate that he is set to direct DC's "Batgirl." He will write, direct and produce the project. I don't get it, they couldn't get him to direct "The Batman" instead? That would have been his ultimate dream job, but he'll have to settle with "Batgirl" which, nevertheless, seems like an interesting venture.
If you are unfamiliar with Whedon, although why would you be, he's the creative mind that penned "Buffy," "Serenity," "Toy Story," "The Cabin in the Woods" and "The Avengers." 
"Batgirl is flying solo. The superheroine is getting her own standalone movie from filmmaker Joss Whedon. Whedon is nearing a deal to write, direct, and produce an untitled Batgirl pic for Warner Bros. as part of its DC Extended Universe. No other producers are currently attached. Toby Emmerich, president and chief content officer of Warner Bros. Pictures Group, is overseeing with Jon Berg and Geoff Johns. The new project originated in the past month. Whedon would be making a big move from the Marvel Cinematic Universe to its DC counterpart, having written and directed “The Avengers” and “Avengers: Age of Ultron” for Disney-Marvel. He also created the television series “Buffy the Vampire Slayer,” “Angel,” “Firefly,” “Dollhouse,” and “Agents of S.H.I.E.L.D.