Persona 3 Reload wasn't the "complete experience" that Atlus had promised, but the development process for Episode Aigis was apparently so chaotic that it nearly didn't happen. In an interview with Famitsu, DLC director Yu Hashizume and creative director Kazuhisa Wada explained why developing Episode Aigis was so difficult, and why it had to be removed from the original release.
"There were a lot of difficulties that had to be overcome in order to make the remake a reality, with challenges from the outset of the main P3R project," Wada said. "As a result, we had to abandon the remake of Episode Aigis." It wasn't until after Persona 3 Reload was announced (and the team saw an outpouring of support) that Atlus decided to give the epilogue a go.
