Agree 100%. The chance of the high multiplier is precisely why many players purchase it, not because it is killing, but because it is a "fight-stopper". With normal attack dice, the more dice you roll the more average the result is likely to be. A 12d6 Normal attack will probably do about 42 Stun. But with so few dice the chances of the roll being average diminishes. An equivalent 4d6 Killing attack, with only average rolls on the BODY of 14, can quite possibly do 70 Stun. A Multiplier roll of 4 does the same 42 Stun on average, 56 with a roll of 5, and 70 with a roll of 6. So a player is gambling on his 50% chance of doing average or better damage, with a good multiplier roll quite possibly ending the fight in one hit.
One of the things about 6E that most saddened me was that they didn't correct the KA travesty. The Killing Attack mechanism is broken, and always has been. This isn't Steve Long and DoJ's fault; they inherited it when they bought the game system. It should probably have been eliminated in favor of using Advantages like Piercing, Penetrating, or Armor Piercing to simulate damage from bullets, swords, lasers, and the like.
EDIT: I am reminded that 6E has changed the Stun Multiplier to 1-3; which is one of the few changes in 6E I like. I was speaking of 5E and previous versions. I still dislike Killing Attacks and the whole Multiplier method, but the 6E version is at least somewhat better.