The most important consideration in reversing campaign laws was the protection of free speech for all. Particularly political speech, and specifically any and all dissenting viewpoints. If the government has the power to curb political speech it finds undesirable it becomes open season on liberty and we all become losers.
The Cato Institute puts forth a compelling and objective argument for restricting the governments power to control or prevent free speech and expression of thought, and why the Supreme Courts reversal was appropriate.
Via: Cato Institute