Mate,
I'm moved to post on this, firstly in warning. You're coming across as violence obsessed, and it doesn't do you much credit. I'm sure you're not, but that's how it's coming across. You sound like you've had a tough time of it, and now you're looking to vent.
Here's my twenty pence worth:
Killing with your bare hands is really hard, regardless of what you learn. At their root, most Martial arts were designed for this purpose. Taekwondo is taken from the style of fighting the Koreans used in their various wars of liberation/self destruction.
The point about them now being 'solely about killing' is a bit irrelevant. If you want to kill, go and get a knife, or a bow, or a gun. All of these devices were devised to kill without needing massive amounts of special training. Yes, you can train as a marksman, but you can also learn to shoot someone in a few hours. If you want to learn to kill, join the Army. They'll teach you how to, and teach you it's not actually that difficult with the right tools.
The physical and mental conditioning of most martial arts - I speak from experience about several - is two fold. Firstly, the physical conditioning is so if you have to fight, you can. However, that discipline and spirituality which you seem to have such little time is equally important. Without that, you easily find a situation where you would start a fight, just to show what you can do. That's a power trip, showing off, and it's the easiest way to be. What the discipline should teach you, like any warrior, is when and when not to fight.
Ironically enough, the more you learn, the less you will fight, because you don't feel the need to anymore. That's why you learn it, so, when the shit hits the fan, you can keep your head, assess the situation, and react accordingly. That will probably be non violence. It'll stop you just going nuts and smashing in someones larynx by accident.
That's what they are really about, today: self control and control of a situation. Not killing, because we as humans have invented many hundreds of easier ways to do that. Martial Arts were superseded many, many years ago in that regard. And if you were have to kill with your bare hands, I pity you for what that would do to you.
The art stays the same, the purpose changes.