Classical music is NOT responsible for John Williams. The man writes decent music, except that it is ALL movie type music and based on fundamentally the same major chords! If you take all of John Williams' music and listen to it back to back, y'know the one sound track that sounds different? Indiana Jones!
For the love of all things, do NOT write off Classical Music as a crappy idea because of John Williams! Write it off if it's not your thing after you listen to the good stuff, but not for John Williams! That'd just be letting that over puffed turkey win.