So
This "any attack may be lethal" is not new to 4e, it's pretty standard warhammer fare. In 2e, you rolled a d10 for damage and if you rolled max, it triggered "Ulrich's Fury". You rolled again to hit to "confirm" the effect, and if it hit, you rolled another d10 for damage - and if that one rolls max, you just keep rolling (no need for confirmation). So a single goblin arrow can kill a powerful PC. This lethality isn't new to 4e, and I don't think it fixes the problem I have with this "attacking a superior foe helps your foe" notion.