Warhammer 40k: Eternal Crusade is positioning itself to be a blend of MMO elements with third-person shooter elements, and like its source material that means everyone's trying to shoot everyone else. So you're going to need a way to communicate with other players, and if typing out "please help me shoot these guys" is going to take too much time, you'll need a voice chat solution.
The development team behind the game has taken this fact to heart, and rather than forcing players to rely on a third-party solution, it's working on integrating the Razer Comms system into the game directly. This also includes filters to help you fully immerse yourself in the setting, tying the game's normal sound and voice chat together. If that sounds like something you'd like to see in action, take a look at the full announcement for more explanation of the integration and what it offers the players.