I admit to being a John Williams fan. He has (IMHO) done more for classical music's re-emergence into mainstream music than any composer of the last 50 years, mostly due to the large number of film scores he's produced (and awards he has won).
However, he's also been criticized for being too neo-romantic in his music, not adventurous enough. Well, below is a YouTube video I came across that perhaps shows why John Williams sounds so neo-romantic - many of his themes (and orchestration) are nearly identical to recognized classical pieces by Stravinsky, Holst, Tschaikovsky and more.
AlexLieb2802 is the author of this clip with many more examples on his user page located here: www.youtube.com/user/AlexLieb2802