I say, more death, less injury. Especially from assassins. I don't think I've ever seen an actual successful assassination attempt in the entire game. I'd prefer not to imagine a fantasy world where every assassin is spectacularly incompetent.
I agree with everything you said, ergo my mortality feature request some time ago... but I wanted to point out that "successful" assassination attempts have been confirmed to be impossible. It's not even in the code to cause someone to die as a result of infiltrator action. In fact, "assassination" has been called a misnomer propagated by players. I'm too lazy to find any one of the several threads where this was analyzed, but
most of the infiltrator text says nothing about killing, only about wounding or crippling. It was never intended for infiltrators to be assassins; if I remember right, Tom had explained that outright murder (duels to the death at least give the other guy a shot and militia is disposable) would be beneath a noble, but a little handicapping to get ahead is a-ok.
So think of it this way: It's a fantasy world where there really are no assassins, just a bunch of normally respectable nobles willing to pick up the medieval equivalent of a lead pipe to kneecap the competition.
All that said, I don't necessarily buy that explanation, either. In my mind, it should either be full-on assassination with weighted chances to fail, wound (varying degrees), or kill... or nothing at all. If the intent of an infiltrator was to be a spy, playing the game of intrigue and espionage, give him options to gain information and sabotage things, not attack people.