BEVERLY HILLS, Calif. — Times weren’t previously as dangerous for characters on scripted prime-time series. Earlier in TV history, series regulars were rarely killed off. Which explains why the death of Henry Blake (McLean Stevenson) on M*A*S*H had such an effect. Today, it seems ready to cut down characters during a midseason finale (bye-bye, Beth of The Walking Dead) or at any random point (R.I.P., Will Gardner of The Good Wife).