Is there any reason or symbolism for choosing such a style for the song?
IMDB's trivia has this to say about the song.
"King Herod's Song" is based on "Those Saladin Days", from "Come Back, Richard, Your Country Needs You," a failed Andrew Lloyd Webber musical for schools about King Richard the Lion-Hearted and the Crusades. Tim Rice wrote new lyrics, first as 1969 Eurovision contender "Try It and See," and then as "King Herod's Song" for the album, show, and film.
So it could be said that they were trying to fit an already written piece of music into the show.