It has been suggested that it doesn't matter whether Noah's flood and other stories in the scriptures actually happened.
I would suggest that the reality of the literal global flood in the days of Noah matters.
Here are some reasons why I believe it matters.
1. Ancient and modern prophets have taught that the flood literally happened. The world wide global flood is spoken of as a literal historical event in the Old and New Testaments (including the JST) and in the Book of Mormon. From the days of Joseph Smith to the present, the leaders of the church who we sustain as prophets