A collective benefit
If freedom of expression were only an individual right, a majority of people saying “I don’t care about all this stuff, I have nothing to say or hide” would be enough to legitimize censorship and mass surveillance.
By the way, it is important to note the individualistic vision of this type of comment “I don’t care if my neighbour has things to say or hide” which has as corollaries “I don’t want to hear what he has to say” and “if he has things to hide, it’s illegal”. Of course, individualism is part of the evils that plague our societies, but it is another subject.
But freedom of expression is also a collective good, and it is as such that it must be protected. The question of course guides the answer, and the question to ask to reflect the collective aspect would rather be “do you blindly trust the authorities in place to defend the collective interest?”
In other words, even if we have nothing to say or hide, protecting freedom of expression concerns us all equally.
Of course, all powers impose limits on freedom of expression.
These limits are sometimes acceptable and generally accepted by the population: this is the case in France, for example, with hate speech, terrorist propaganda, child pornography, etc. The US has even included freedom of expression in the first amendment of its Constitution: there the limits are wider (but note that if the Nazi party is allowed, disclosing means to read DVDs is prohibited by the DMCA).
Unfortunately, most people in the world live under authoritarian regimes and suffer from restrictions on freedom of expression designed to suppress dissent and ensure the stability of the regime. The pretext is invariably the preservation of public order, and perhaps some citizens believe it.
But on the Internet geographical borders are obsolete, we can no longer restrict ourselves to thinking at the local level of a country or a continent.
These prerequisites are necessary to understand that if mass surveillance and censorship are possible on the Internet, they will be abused to oppress most of the world’s population.