Greg Rucka announced on his Tumblr his reasons for leaving the title with issue 25
“Writing Diana again has been an amazing experience, on the level of a dream-come-true,” “All any of us who’ve worked on the book this last year have wanted is to serve her well, to illuminate what we so absolutely believe makes Wonder Woman such a remarkable and unique and timeless and important character. To have had that opportunity is something that I doubted I would ever get again. Most of us don’t get a single bite at the apple, let alone two, you know? To get that opportunity at a time when Diana is rising to such (long-overdue) prominence makes that apple all the sweeter. That she’s turned 75 during the course of our run is–to ruin the analogy–icing on the cake.
“We started Rebirth with a specific, though fairly broad, mandate from DC. ‘Bring her back to her core,’ was what Geoff Johns told me,” Rucka continued. “How we did it was up to us. Our success in doing so is measured, of course, by you. ‘Wonder Woman’ 23 sees the end of our ‘primary’ storyline, ‘The Lies/The Truth,’ and ‘Wonder Woman’ 24 serves as something of an epilogue to that tale. ‘Wonder Woman 25′ will, I hope, set a table for who is to follow, and provide for them as much room to work and explore and grow. Diana’s future is bright, that’s what I’m saying.”