Why did the proposal of Martin Van Buren and the committee on suffrage arouse such heated opposition at the New York state constitutional convention in 1821?

Because it suggested that all white males should have voting rights

Explanation:

Voting rights in America has been very contentious, with restriction placed on different categories of people ... whites, males, females and blacks. These kept changing over the years and centuries accross different states in the United States. Martin Van Buren and the committee on suffrage suggested voting rights for for all white males in 1821 generating heated opposition.