Savage Worlds combat can be wild and explosive. This can be fun and amazing...and some people find it anticlimactic when a Big Bad is blasted by one exploding hit, inflicting more Wounds than can be realistically soaked without a similar bout of luck on the Soak roll. So I propose a modest solution: Plot Armor.
Plot Armor - When a Wild Card makes a soak roll and fails to soak all Wounds from an attack, they may immediately spend a second benny to soak all the Wounds from the attack. However, the spent benny immediately goes to the attacker's benny pool as a reward for forcing the Wild Card to use the Plot Armor. This does not remove any existing Wounds.
The idea behind this is that it removes the possibility of a Wild Card being wiped out in one hit, but also helps rapidly deplete the Wild Card's resources and rewards the attacker so it doesn't feel as though they were completely ripped off.
Obviously, only use this if you have a problem with one hit kills. I don't, personally, and we've gotten great stories out of one hit kills, but it's a common enough complaint about Savage Worlds that I thought I'd toss it out there.