I'm pretty surprised to see you lump Shostakovich and a hack like John Williams together. I definitely don't think John Williams is a worthwhile composer. Shostakovich, on the other hand, was a serious, troubled composer who, while not necessarily an innovator, is a very worthwhile composer IMHO. You're obviously free to feel any way you want about the music, but history has proven Shostakovich's worth as a composer and, in turn, has been quite kind to him. I can't predict the future, but I can honestly say that Shostakovich will probably enjoy a nice, fruitful existence in the concert hall unlike someone like John Williams who didn't compose anything that could be taken as a piece of art. All in my opinion of course.
As far as Lindberg goes, I found his early music to not be very distinctive. It's just one wash to me. There's no substance or variety in the music. It works completely on a dissonant level, which doesn't necessarily appeal to me. I like composers who can provide relief from the dissonance. Thankfully, for me, Lindberg's later music has proven to be quite good and contain plenty of melodic ideas that help me access the music. There's still dissonance, but there's plenty of access points that help guide the listener along. For me, Graffiti is one of his better newer compositions. Concerto for Orchestra is also enjoyable. Of his early music, I do like Kraft. I think that's one of his better works from this period.
Anyway, we enjoy what we enjoy and that's all that matters in the end.