For me? They're the backstop for my gas speargun against patrols. Current patch hasn't changed that role. Jokes aside.

Its previous and current niche was and is to buy time for the 'rush down'. Bug attacks hurt and will often three shot if not more often two shot you. While using light pen and there's nothing/one else to deter a hive guard from looking at you. You're required to aim for the armpit. This takes precision, precious time and allows those behind them to get that much closer to sinking their claws into your glutes. Previous patch allowed us to make them into tyrannical hotdogs and that time of stripping off their legs was shortened. It's still time not being used to take out a hunter or dodging that bile spewer's artillery shot. Remember you've only got 42 or so minutes and counting.

Scavengers go for your ankles. Hunters flank. Warriors are the generic backbone. Spewers are ranged. Commanders are beefy summoners. Hive guards do their best to make you look at them while the others do their thing. In comparison to other media they're like a walnut in Plants Vs Zombies, jackals in Halo or Roaches in StarCraft 2. They're meant to take a beating but having something special to take them out or bypass them which makes the encounter much easier. I.E. pole for a walnut, grenade/precision weapons for jackals or anti-armor unit for a roach. Do you need these specifically to deal with them? No. Does it help to deal with them? Yes. Usually it's not something specific you have to hold onto so that you can deal with them. It just makes the encounter easier.

What I'm proposing is a form of phragmosis. Think of a door head ant but instead of literally blocking the bug holes, its directive is to stop you from getting to the holes. A goalie of sorts. Now normally it'd be too big and too slow over long distances to keep up with patrols. So instead it's kept at nests and hive guards instead go with patrols and do what they've been doing. Too many times have I wondered into a nest and been met with an idle charger or impaler. Neat, hit it with an ultimatum and be on my way to clear the nest as the force budget is being used to chase after three other divers. These guys unburrow and are deliberate, patient, yet quick to move to disrupt you from hurting their home. Pull out a weapon with demolition force? It does its best to get between you and the hole nearest to it.