What did you do, look up his name on Moby Games with no idea what he actually contributed to those titles? Backyard Wrestling? Without even bothering to look at the credits, I'm guessing he's listed under 'Special Thanks' at most.
More importantly, did you know you can finish DX:IW without killing anyone? Or using a weapon at all? Spector's games have been pioneers of player choice, including the choice of whether or not to use violence. They might have violence in them, but to draw any sort of comparison to GTA's content is ludicrous.