I have to disagree. While John Williams is the best the new scores are really good. They shall use this. To make the films hopeful we can't simply change the music. One thing i loved about MoS and BvS are the scores especially that of MoS. Yes they are not memorable as Williams because they are not catchy. But i really love them.
A lot of people loved the latest JL trailer released in SDCC. An important part was its music which takes cues from the Man of Steel Main Theme. This theme is also hopeful and inspiring. The reason we feel Superman to be less hopeful is the writing but the them is inspiring and powerful. This can't be as influential as John Williams. After all who can? That man was a legend.