It's too bad Bioware decided to eliminate the ability to kill companions, but I can see their point of not wanting to deal with the massive crying of "I didn't know they would really die!, as pointed out in the last podcast. But, there could be another solution. Perhaps the first time you attempt to kill you companion they escape and you are forced to live without their talents for a several weeks or as much as a month as a penalty, and then you are given the chance to redeem yourself or execute your original plan. Let's say the companion escapes and time passes. At that point the player is presented the opportunity to hire a bounty hunter to track the companion. After several payments of credits they get word of a planet where the companion might be hiding. There could be a quest chain such as one involving the companion's imprisonment by the hut's, and in the end the companion is rescued and is allowed to join the party. Or if you are a true Sith, you recue the companion and teach them escape was never an alternative. After all of this, if Bioware wanted to give you another chance, maybe in another 10 levels or once hitting max level the player could pick up another companion with the same skills, but as a penalty the companion would be would need to train up to your level. And at that point if you decide to kill that one, you either don't need them or are a dumbass and deserve the penalty.(source):swtor4credits
I just do not see the point of killing off your CCs. Why do so many people like this idea? It puts you at a permanent disadvantage in game for the rest of your character's existence on the server. Why would anyone want to do that? If you just want the challenge don't play with your CCs. Leave them on your ship and pretend they don't exist. Having the option to accidently kill off your character would drive me nuts. Knowing that I have played many BioWare games and have made choices that have killed off companions not knowing that they would die before the choice, I am not a fan. It isn't so bad when it is a game that ends, but playing an ongoing game like an MMO it would really stink.