The Assault class is absolutely underwhelming. The grenade launcher isn't that great in my opinion.
The grenade launcher is great. No complaints there. Assault is underwhelming because the Adrenaline injector is absolutely useless. The duration is way too short to even make something happen before it wears off again. Compared to how long it lasts, it actively puts you at a disadvantage due to the time it takes to inject yourself.
They could have given Assaulted either c4 or some sort of breaching charge that takes down walls
This isn't needed because every single class can equip the sledgehammer.
Engineer is great, but they launchers are so underpowered except for the rpg.
Lock-on launchers can lock-on to painted targets from the laser designator or tracer dart, while the RPG can't. The MBT-LAW has the advantage that it does not need to care about which side it hits the tank, because it will always do a top-down attack. It's only the Aim-guided launcher and RPG must be shot at the back of the tank to do the most damage. The Javelin has the advantage of potentially having a much longer effective range. It's just a matter of trade-offs.