1.) Wolfman told him he really didn't think he had anymore stories to tell with the Titans. The guy told Marv to think of the craziest ideas he could imagine and mentioned the Wildebeasts as rogues he liked. Wolfman and him conceived that arc with them as the main rogues.
2.) Spin-off books. Deathstroke was the popular character and he asked Wolfman why he never let him be in Titans as much. Wolfman never really seemed to give it that thought the popular rogue could work in a series. As the editor claimed , he pictured Slade Wilson as their "Wolverine" type character and wanted him to get the 1st big spin-off series. DC told them to judge reaction from Titans #70 to see how it work. Once reaction was good enough , Deathstroke got his own series.
3.) Another spin-off was Team Titans. Which would come outta the Total Chaos arc. This one happened.
4.) Before the editor left , another spin-off series was gonna be called The Hybrid (I believe that was the name). It was supposed to be in the 3rd big arc leading to #100. But he left and the plans seemed to go to shit as the Batman editors pulled Nightwing from Wolfman and Zero Hour was around the corner.