In the words of American poet Ezra Pound, "Great literature is simply language charged with meaning to the utmost possible degree."
Incontestably, then, plot is subordinate to style. In literature, that is!
In cinema, I reckon the opposite is true.
To adapting literary masterpieces on film, therefore, I can come up with only one reason, namely to sell heaps of tickets to people who for some strange reason prefer to see films showing characters they are already familiar with.
Otherwise : What Is The Point??