Ubisoft offers up a brief explanation as to why Watch Dogs for the PC contains some hidden graphical options.

It's odd though as many people making use of the settings have said that adjusting these hidden settings actually reduced stutter, improved performance in some cases, and made the game look better. Even if Ubisoft's reasons are true and there was no "downgrade" on the PC version, then there was an obvious falsified "upgrade" version used for their E3 presentation.