FYI: Assault class captures objectives faster, they run faster, transition to ADS/change weapons faster, can carry 2 weapons (with split ammo of course) so you are never at a range disadvantage, they have frag launchers for demolition and AoE damage, stair/ramp gadget that can create totally new advantage points that your enemies are 100% not expecting and their assault rifles perk is pretty good compared to the others.
Now is the spawn beacon change good? Nope, it fits way more on recons, is their adrenaline syringe good? Nope, awful, the worst of all the classes by far; but saying the class is useless is a wild statement.