1. Everything other than foot soldiers are robotic. They are called "Zealots" for a good reason. Why risk your life when the bots can do all the killing while you sit back and eat popcorn?
2. Your foot soldiers don't just "die" --- their armor units each have a built-in teleportation gadget that bails them out when they got critically wounded.
3. They then go back to their homeworld, where they get converted to mind-in-a-tank cyborgs (which is responsible for the "hydraulic fluid" you see when a Dragoon dies).
They do, but their "shtick" is unit preservation: all their units have regenerating shields, and their units generally have high health/cost. Some of them have additional protective abilities, like the Sentry's damage-reducing aura, or the Immortal's Barrier. Finally, when raw shielding/toughness isn't enough, many of their units are quite mobile, allowing wounded/deshielded units to retreat.
