Grimm has it right.
Start messing with lethality and hardness and the game changes from being a simulator to being super mario doom with wings. I've seem some bad ideas to help "balance" the arena, but messing with lethalithy and hardness is about the worst I've seen. The AI ack already occasionally interferes with player vs. player gameplay (ie. when getting picked out of the sky by heavy ack during a dogfight by a gun you're not anywhere near) but messing with the lethality and hardness just turns that whole AI and ground attack simulation into a big unrealistic chocolate mess.
I really hope that doesn't get changed. Like Grimm implied, as long as you're messing with the core SIMULATION part of the game, there's no reason to not start adding powerups, space warp portals, and all the rest. All in the name of gameplay balance of course...
I'd rather get vulched by the horde than have to guess what version of AI and arena "reality" I'm fighting at any given time.