While not "REMOVE OUTRIGHT," I need to address something that outright bugs the shit out of me about Inversion:
SPAWN CADING:
That is, if you haven't figured it out, placing cades right at a spawn point, trapping zombies in place [since you spawn with the board going through you pretty much] and giving the opponents free kills. Times like this where I wish HL1 spawn death [from multiple people spawning in the same place simultaneously, or on top of each other] still occurred. >_<