The difference being that Hikaru is, for the sake of argument, the central character in Macross. We follow the events of the show through him. Had he died 1/2 way through, then the writers would have had to "promote" one of the supporting cast to the leading role. In Troy, however, there's several leads. And one of them (Hector) does die 2/3 of the way through, and he's arguably the hero of the entire film. So there!