Hey, just joined Tapas but I love this topic. Death can be a great motivator, but as you've all said, it needs to really show on the MCs or MCs closest relationships, otherwise what's the point? If characters just go, "Oh. They're dead," and then get back to business, with no real repercussions to be seen, heard, or felt, than why should the reader get interested in these characters, both the ones living and the ones now dead? We will all feel grief in our lives, and that should be a way to relate to characters.
Oh, and random deaths like those of GoT and TWD just become, "Oh. They're dead. Oh, well, back to work!" And unless there is a genuinely stated reason why, the dead should stay dead, and the story universe all the worse for it (as in physically, not literally... if that makes sense? As in characters WILL suffer because someone/some people died). So in stuff like Green Arrow everyone... stays... dead. I stopped watching quite early on when uninteresting characters kept getting resurrected.
Again, great topic!