[quote name='evanft']Or maybe the content on the disc was unfinished or left incomplete because of time constraints and they unlocked it/completed it later. Could happen.[/quote]
That seems plausible. They found code on the game disc referencing the new plasmids, and other plasmids not in the orig game.
But if you look at the code for any game, there will be stuff in there not in the actual game. Time contraints, development choices, etc. The developer doesnt always have the time or desire to clean all that stuff out of the code onthe disc. Hell, look at Hot Coffee, Or KoToR 2.
The Plasmids could have been planned from the getgo, but never completed, yet still mentioned in the games code. This 20mb could be the actual graphics for those plasmids, which would take up that amount of space.
Either way, it in no way smacks of withheld yet finished content.