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.
"The development team, led by director Takuya Yamaguchi, was focused solely on the development of the main story, so there were almost no resources to devote to the [epilogue]," Wada explained. "I had very little time to spare, but I was thinking of going back to a director position and working on it if the opportunity came up. However, one day, I received information from another team within the company that it might be possible to assign a staff member from there with directorial experience."
This is where Hashizume came in. Hashizume worked on games like Soul Hackers 2 and Radiant Historia Perfect Chronology, but wasn't part of Reload's development line—which is apparently pretty unusual: "We were in such dire need of talent that we had to make an exception."
Earlier this month, Atlus confirmed that Episode Aigis would be part of the expansion pass: "The three parts of the expansion pass will not be available separately and only available as part of the full pass," an Atlus spokesperson said, talking to Push Square. This means you'll have to buy the entire expansion pass for $34.99/28.99 if you want to play Episode Aigis. You also get other perks like more background music from Persona 4 Golden and Persona 5 Royal and additional costumes, but for those who simply want to experience the entirety of the Persona 3 story, this may not sweeten the deal.
While paid DLC is not uncommon, the problem lies in Wada's comments during an interview with Gamerwk (translated by Persona Central) a few months ago, which explained that "fans can rest assured knowing that Persona 3 Reload offers a complete experience."
Episode Aigis will be released in September, and despite my excitement for this DLC, it really does sting to know just how close we were to getting a remake of Persona 3 that included everything.