Why is judicial independence so important under our system of government?

It is important because if the judges are sided with a party or with a faction then they could make decisions that support the party or the people in charge and not make unbiased decisions on law related things. For example, if the president who sets them was from a party and they were supporters of that party, then they could make choices that the president wants and not what they think is right, which would make the judicial branch then just a hand of the executive branch.