What Walking Dead do isn't killing their major characters like flies. But to give the feel of desperate life of their major character in the forsaken world. They give us a feeling that every characters can dead anytime (even when they were always survive), and when they survived, it gave us a relieved / happiness; because our hero / heroine will return in the next episode.
So basically, Walking Dead is raping their characters and push them all into the wall. Sometime, I feel sorry for them (the characters) and hope that they will find a safer place for their live.
Star Trek was different. They didn't give us the desperate feeling like what we feel from Walking Dead. And they didn't give us a massive characters conflict like in "Lost". They even lack of character development. The season 1 Kirk is the same as the last TOS Star Trek Kirk. The season 1 Picard is the same as the last TNG movie Picard. They are not change. That's why, sometime I want to see Picard as Admiral rather than the "forever' Captain.