User blog comment:DeadpoolN7/Future DLC/@comment-24.60.42.14-20121206123629/@comment-24.60.42.14-20121206183450

That depends, however, Bioware constantly said Omega was the largest dlc they ever released which was quite true since it was about 1.9 gb. Bioware probably left the Omega Nebula out due to the file size of the Omega which the dlc space limit on the 360 is 2 gb. The limited space likely made the Bioware team cut some corners, so the story they wanted was left somewhat intact without portions being entirely cut. Besides they can always add the systems later on without having to increase Omega's file size.