I'm loving Savage Worlds too. It's a recent find for me; I use it mainly for Deadlands Reloaded and Realms of Cthulhu.
I can only go by Savage Worlds:Explorer's Edition, but I find that even without tweaking the player character lethality has more to do with how reckless the players are than the exploding dice themselves. Even being incapacitated doesn't kill a PC most of the time.
However, if you are truly being reamed by the mechanics, the obvious answer is to limit the number of aces any one damage roll can have. One per die would seem to be adequate. Of course, your players may demand that the rule doesn't apply to their damage rolls, players being what they are. This sort of behavior should be greeted with your "yeah, right" face.
NPCs are virtual people too.
And of course, there are all those bennies (though they can't alter a damage roll unless a particular edge has been taken) for re-rolling soak rolls, vigor tests and so on.
Sudden Thought Department: One common misconception I've come across is that you should add a D6 per raise on a combat hit, when the rulebook clearly states that one or more raises gets you a single extra d6. One game I watched had a very high lethality on account of this one small misreading of the rules alone.