We The People . . . establish Justice.

Justice
is rendering to every one that which is his due. It has been distinguished from equity in this respect, that while justice means merely the doing what positive law demands, equity means the doing of what is fair and right in every separate case.
Source: Easton's 1897 Bible Dictionary

The Founding Fathers knew all about injustice.
It was still early in the Age of Enlightenment. Voltaire and Kant were both still alive. Slavery still existed, and so did serfdom. The Revolution came about because the rebels refused to help pay for a war Britain entered into in order to have some say in the selection of the next Holy Roman Emperor. The common man of Europe lived a life that would make your average Charles Dickens character look like Paris Hilton.
The worst part were the courts. Judges were the servants of the nobility and the Church, and were employed to make sure things went the way the Church and the nobility wanted them to. Corruption was all but universal.
This is why Establishing Justice was number two on the Constitution's list of goals.

Justice (n)
1 The quality of being just; fairness.
2a The principle of moral rightness; equity.
2b Conformity to moral rightness in action or attitude; righteousness.
3a The upholding of what is just, especially fair treatment and due reward in accordance with honor, standards, or law.
3b Law. The administration and procedure of law.
3c Conformity to truth, fact, or sound reason: The overcharged customer was angry, and with justice.
Source: The American Heritage® Dictionary of the English Language, Fourth Ed.

The Founding Fathers made the establishment of justice second in their goals for the Constitution. They knew that without justice there is no law, and without law there is no democracy. But they knew also that without equity there is no justice. Where people are not equal, then democracy is a sham.
There is little equity today. The famous, like Michael Jackson; the rich, like Ken Lay, are all held to different standards than you or I. Money and influence can delay or derail laws.
The reason the Founding Fathers separated the Courts from the State was to prevent inequity like this from building up. They knew what happened when the rich and powerful ran the courts, and they set up as many checks and balances as the system would tolerate to keep the courts beyond the influence of the influential.
We need to keep things this way. However good the intention, any change in the functioning of the courts which would give any advantage to the rich over the poor, the corporation over the individual, the church over the state, or the state over the citizen will only destroy democracy.