It’s meaning is that we value freedom of speech, and the right of everyone to express their opinion, even if that opinion is one we do not like. Unless we all have free speech, none of us really do. An open society is only possible if the government allows everyone to make their views known.
In terms of applying to to “our technology-oriented future” the value of free and open debate is still important. The concern for many is that the ability to disseminate ideas is no longer controlled by the government. It is largely controlled by a small number of large companies. If those companies decided to silence someone by barring certain speech on their systems, they effectively have a censorship power that was once only available to governments that did not respect free speech.