Hello,

as the devs stated in their official steam statement, the game is 100% lore accurate.
Yet there is no lore reason for so many weapons to be locked for other classes.

There is even less reason when it comes to gameplay.

For example, Assault and Bulwark class. Bulwark class has a shield they can use at any time.
Assault class has nothing. No buff to melee damage. Using your jetpack charge to dodge takes it away from being able to use it to do damage.

Unless damage is scaled up, I truly, honestly see absolutely no reason for Assault and Bulwark class to not have primary weapons.