Many other FPS games are available, with high movement sci-fi FPS shooters and character-based team shooters both being a big trend this gen.
An art style and game name that settle pretty comfortably in the sci-fi shooter mold without sticking out too much or having much of its own identity. The ads/E3 coverage for this game blended in with all the other sci-fi FPS games we're used to rather than sticking out as something new and unique.
A lack of well-defined or interesting characters for players to attach to during the marketing phase and think "I want to play as that dude."
And this might be the hardest pill to swallow...
The game isn't that interesting. The combat mechanics are great, the shooting is nice and punchy, and low-grav areas make for some interesting arenas, but as a whole it doesn't show too well in advertising or streams. The maps have a samey grey look to them, the characters are indistinguishable from other FPS grunts, and as a whole the vibe of the game fails to do something really attention-grabbing.