In Gothic I you vere never on TEH QUEST TO KILL SLEEPE!ONE1. The knowledge about the sleeper and what he represents was obtained through the quite entertaining story with lots of twists and fairly good dialogue/narrative side. Necessity to find and shut down the Sleeper only aroused in last chapters, which, granted, were quite booring compared to the early game.
In Gothic II the story was eqally entertaining and surpirising at times (especially with NoTR), and what's more important, it was executed very well. It wasn't just about finding and killing TEH DRAGONS, there was a lot more to it.
That said, both Gothics, first and second weren't really an rpgs and they were never hyped as sutch, although wastly ritch and detailed gameworld, lots of freedom in exploration and ability to choose sides made them a whole lot better than most of the self titled rpgs, that came out at that time and later on.
Gothic III, although i somewhat enjoyed it, had lost about 80% of every strong side, the things old Gothic admirers loved it for the most from what it's predecesors had - world is big, with lots of NPCs and quests, but it's all quite generic and leaves unsatisfactory feeling of copy paste world so familiar from TES games. Main story just doesn't happen. It's absent. Look at Xardas. Oh my...
Oh, and combat is non existant too, i would rather prefer stupid RTwP bioware shit, than this non-combat clikckety-clicking mundane madness and that tells a lot.