Inasmuch as different parts of society disagree on how to "improve" it, one part does not have the right to censor the other.
Free speech is an amoral tool, which can be used to improve or degrade the human condition, when wielded appropriately. It's our job to decide when and how to use it, and not act naïvely and pretend it's a virtue in itself.
Soviet censorship vectors were able to wrap dissenting viewpoints as "counter-revolutionary" or "bourgeois" without regard for the consistency of content to the wrapper.