Sometimes people should die, sometimes they shouldn't. It's all about the tone you've been building. I've not actually played or finished any of the games you spoilered (shouldn't have clicked the smurfing tags ) but I know that (SPOILER)in Mass Effect 3 there is not nearly enough of a feeling of "oh smurf we're losing." I know it gets worse, but you're always progressing towards victory, just like in the previous two. So having Shepard die is a giant cop out.