That's because economic justice is a slogan, not an actual plan. From what I understand of it, it's where everybody would be at the same economic level. The rich would become poorer, the poor would become richer, and the middle class would become...well, more middle class.
Guess which group made up the majority of the fans of economic justice during the “Day of Rage.”
You may have noticed this, but people have different abilities and skills. Naturally, that will make them better suited for certain tasks, which can put them in great demand. By the same token, they may have shortcomings where their skills wouldn't be desirable. You may want to pay an NBA superstar millions to dunk a basketball, but you wouldn't pay him to perform brain surgery. (Not to mention, the NBA star-come-brain surgeon might try to slam dunk a patient's brain back into the skull, which opens up a LOT of malpractice suits.)
What I'm saying in short is people are different and, thus, their ability to make money will also be different. When there are differences, equality can only come from two sources: by agreement, or by force. The former requires all parties to agree to an outcome. The latter requires at least one party to agree to an outcome and the subjugation of those who disagree. Right now, those who push for economic justice are trying to persuade. When that fails, and we know it will, it will require force to create a system of equality.
Of course, that's already been tried. Remember the former Soviet Union? Yeah, that didn't work out too well.
The Soviet Union learned the hard way the problems with forcing economic justice. The people involved with the “Day of Rage” on Wall Street haven't.