All these names, we named ourselves. We named the hive because they have a kingdom the cabal we call then that because they re reminiscent of a roman empire, the fallen were nobles and we name them as such. It doesn't make sense that these races have English names for themselves when they speak alien tongues. We named ourselves something intimidating when we're top of the line killing machines? Yo, we're black ops man. We go in to enemy territory with no back up, in small fire teams and fight against incredible odds and have awesome names.

Hmmm... Maybe. But think about it: If the traveler IS the bad guy, and we are the only ones fighting on it's side... Doesn't that make the rest of them the good guys by default? (Does anyone remember that footage of how the Black Garden was supposed to look like??? It was like you were on the inside of a sphere. What is the Traveler? A sphere. Then what do you do in the mission? You kill a HEART. Only living beings have a heart. And it's a black heart, a dark heart. In storytelling, somebody with a black heart is always evil. But then, why do we fight the Vex, as they seem to worship this black heart? Well... The Vex also fight the Cabal. Maybe the Vex are actually on our side and we don't know it: WE attacked THEM, not the other way around. Then towards the end we seek to destroy their God's heart, of course they'll try to stop us. Perhaps the Speaker and the Vanguard have discovered the Traveler is the bad guy and they have sent us to kill it, pretending it is still good to not let it in on their knowledge?)