Game director Sefton Hill argued that it would have seriously diminished the game. "If we did multiplayer then we wouldn't have been able to deliver the quality of game that people wanted--that we wanted," he said. "We would end up delivering two watered down products."
Apparently, the team at Rocksteady did attempt building multiplayer in the game. However, Hill and co. weren't pleased with the results. "We did look at multiplayer early on and we looked at what it could actually bring to the table," he told CVG. "We tried some ideas out but it always felt like it was just there as a requirement."
Although the game ended up shipping with an online pass, the publisher didn't try to sway the team's decision on multiplayer. "We're really thankful to Warner on that. At a time when a lot of publishers said you have to have multiplayer, they backed our ideas for single player."
"You see games where you feel like they bolted the multiplayer on," Hill added. "But if they had taken that effort and put it into the single player, they would have had a better game instead of having a multiplayer that people don't play."