What was the main reason behind the reaction against the Heroic play?

Reaction against the manifold extravagances of the heroic play began quite early. The heroic play could provide romance and heroism, but it could not meet any larger demands.

Soon there was a longing for ‘nature’ and ‘reality.’ Its artificiality, its improbability, its extravagance, its lack of genuine human passion, doomed it to an early and natural death. Reaction began with Dryden’s Preface to Aurangzeb where he bids farewell to his, “long loved mistress rhyme”, is stung with shame at the greatness of Shakespeare and his comparative littleness, and decides to return to Nature. The Rehearsal (1672) set the fashion and henceforth the ridicule of the heroic play became the order of the day.