Gravitational force might be a weak force but it becomes very significant when the participating bodies are of large masses. Besides, it is the fundamental property of matter as wherever there is mass, there is the force of gravity.
Without Gravitational force, many things were not possible. Revolution of planets around the sun is caused by gravitational force. Presence of atmosphere on earth is because of this force as the earth attracts the atmosphere towards its centre. Without this force, earth cannot hold the atmosphere and the atmosphere will escape out in space. So, without this force, even life on earth is not possible. That’s why, Gravitational force is considered the most important force.