The Corporate Sector represents capitalism in its worst form. It operates independently and with out regard to human life or the good of beings. It is supposed to be an evil entity with no redeeming qualities. It is led by ugly greedy beings who seek power through use of droid slaves.
These corporations then team up with member states of the republic (Nemodians) to leverage the protection of the Republic and use the government to block the protection of the common being. They are the perfect villains as they use soulless droids to kill and slaughter low-tech creatures that literally have to climb out of the swamps to fight. Their improbable victory is another David and Goliath story where a little boy saves the entire planet with a single stone... err photon torpedo.
In the sourcebooks and novels the Corporate Sector is often described as a lawless sector of space where smugglers can make good cred and criminals can go on the lam.