It seems to me that the Drengin are just well, your stereotypical "bad guys".
They lack any sort of depth, any sort of character. There are no signs that there is a culture behind them - just a desire to conquer the universe and make everyone their slaves.
They're the bad guys. It's obvious to everyone that plays. But at the same time, there's nothing else. They are simply ... the bad guys. What I think is lacking is a more in depth background and an impact on how that affects them. True in GC2, there was some race-specific dialogue, but that was about it.
Can something be done to address this in GC3?