Dioxine, that's not nostalgia glasses. That's having been able to kill them with gauss weapons where the harpoon guns would do nothing. Hence, at least you do damage rather than just waste ammunition.
Yes, sonic weapons were better, but Zrbite was pretty limited, so equipping everyone with sonic weapons wasn't going to happen until very late, if ever.
Explosives were even better, but using them was a bit time consuming, and you wouldn't be able to get many near a lobsterman when it comes out . . . one per soldier at most. Usually though a couple of alien grenades would take them out fine. (And no, I don't recall what they were actually called.) More notably the problem with explosives is that when you're fighting lobstermen at a terror site, you have a high chance to have those grenades to land near civilians and end up killing them too.
So, harpoons, no damage. Grenades, significant damage with what you can throw . . . a lot of times to civilians too. Sonic weapons, good damage, limited ammo. Gauss weapons, at least hurt and can take them down, and you can make as much ammunition as you can get the money for. Did I get something wrong?
In comparison to how things work in XPiratez . . . that vast majority of regular firearms will not harm a lobsterman at all, and I confirm for absolute certain that the Linux SMG is one of those that will always do 0 damage. You know, something to do with only taking 30% damage from piercing weapons like that. I can't say what the resistances were like in vanilla TFTD, I just know the gauss weapons did something, and the harpoon guns basically did not.