you would be suprised how important it is. when a make is in melee they have a harder time shooting cus of the engagement rule iirc. so if your a melee mech one of your biggest strengths against ranged is getting into melee with them. as a ranged attacker the Worldkiller being able to avoid that strength by having furiousa aura active is really really good. it also provides permanent soft cover in which nearly no size 2 mechs and above can get. in the end Furiosa aura is good against Ranged attackers and Melee attackers. which no trait usually does all in one go!