I don't believe that, some people need to die.
Sure, but just killing a person, the act in itself. What if you are meeting with a few crooks, making a deal, and they suddenly change their original terms, now they want double the caps. You could just kill them and get the wares and keep the caps, you know they are scum anyways. Or to show them you mean business, you draw your gun and shoot one of the goons in the head and state that the original terms will stand. I mean, it's not a bad act to kill these [censored]s but it's not good either. They were no threat to you at the moment, the guy you just shot may not even be as "evil" as his leader, he just need a way to support his family. So that could be evil to neutral karma to you. Let's see about ingame examples... Cook-Cook. He's a r.apist and a psychotic killer, of course he deserves to die. But what if you didn't know that story about him beforehand? You just see him and think "I'mma shoot him for fun", that's pretty bad. Even though he's evil, you don't know that yet, you are not killing him because of his heinous acts because you don't know about them at this stage. You are killing him because you like to kill him, for sport, for fun, for practice. In that sense killing him would be bad. THIS is why karma and morals is hard to do in a game. Oh well, in the game he's hostile anyways and you hear about the fiends before meeting him and probably encountered them before and know they are psychotic killers. But still.
What I am saying though is all kills should be neutral (with all these exceptions I mention of course) because I don't like how easily you become "Good" in New Vegas by defending yourself against fiends or feral ghouls. Killing people in self defence - neutral. Killing people in a faction war (say you join NCR and fight Legion) - neutral. Most kills will keep you on neutral karma, or give you a little evil karma. Some kills could give you a little good karma though, but mostly the act of killing won't be a good thing nor a bad thing and in many other circumstances it will be a bad act. A person who just survives in the wasteland is not a good person, he's a neutral person, he doesn't become good by just killing alone. I think good karma shall be awarded by solving conflicts peacefully, and doing kind acts and quests, which you hopefully solve rather peaceful as well.
So, you kill tons of evil people you will still be neutral. To get good karma you
help people, and not like helping a slaver guild with a shipment of tribal teenage girls to be sold as prosttutes in a nearby town, sure you don't kill anyone but your act is immoral. I mean like, this settlement's well is broken and you fix it. Doesn't matter if they are [censored]s themselves, maybe it was the village of Andale before you knew they were cannibals, you were still being nice to them at that accounts for something in this world. Thing is, with "this world", is that most people probably have neutral karma. It's a dog eat dog world, people survive, people are paranoid of others, everyone has killed someone... What I've been saying as that it shouldn't be as easy to be an extremely good guy as you are right now, it should be easier to stay around the neutral area, probably on the good side of course but not AS good as we always get at the moment (saviour of the wasteland, 100% good).
Then of course it's the thing with Reputation, that should be much more important than karma OF COURSE. There should be different kinds of reputation, like Town Rep, Individual Rep, Faction Rep and Wasteland Rep. Something like that. Gabriel probably has a more layed out idea of it. But what I am saying here is that Karma is your Rep but to yourself. Karma should offer many new speech options, like if you are bad, maybe nice and good speech options won't show up and you get some new, unique "evil" speech options to say instead. Talking with a good person and saying something real "evil" and you freak him out. Maybe you want something of his and he's like "Nuh-uh! How about a please "Please Mister"? Else I'll give it to old man Greg, he always says please mi..." and you're like "How about you give it to me, and I won't have to gut old man Greg alive infront of his wife and grandchildren just because you couldn't give a simple [censored] [item] away without hassle?". Of course there could be a neutral option, and options based of skills like Speech or Barter or something just threatening without being to over-the-top evil like if you have high Strength and says something like "You see how big my hand is and how tiny your head is? Give that [item] to me, please."
If you are evil and are talking to some leader of a faction with doubtful intentions on people's health, freedom and economy (like, a mob boss) you could impress him with some "evil karma" dialogue option.
I am also for Speech being divided into Deception and Persuasion. A person role-playing an evil character that tricks people like "[Deception/Lie] Come on, you can trust me!" but actually they can't trust you, you are leading their caravan right into a raider ambush. I'd love for LOADS more [Lie]-options in the next game. That's why I'd like Deception in there, which would also govern your ability to disguise yourself and maybe cheat at cards.