As far as grimoires go, I think it's because of their experience. Hunters are the oldest class, being the initial scouts and frontier/survival experts. They've experienced everything first hand... Titans are second oldest, building the wall an protecting the city... Warlocks are the newest class, scholars who study the traveler and the mysteries everything, and using "space magic"... So tension probably rises between them because Warlocks have vast knowledge of the enemy and assume they have all the solutions, while the experienced Hunters sit there shaking their heads saying "Thats all fine in theory, but you'll be singing a different tune once you're out there for yourself."