If you look at the political science of it, I think that this firewall is there to mitigate the potential instability of the chinese government. This is not new. I mean I'm okay with critics as long as it aims for progress, but the reality is that you don't just snap your fingers and "tada democracy"! So when you don't have democracy, you will have other ways to have a country that is peaceful and thriving enough. Restricted speech is one of those methods.
If you compare the situation in china with the west, it's not so different: there is still some influence between large corporations and government in western countries, and we don't like it either, and free speech doesn't always solve those problems. It's less corrupt, but I think China has really caught up.
I would be cautious about putting "free speech" on a pedestal. What works for western countries wouldn't necessarily do for countries which don't have the same customs, history, or culture. Free speech is one of those double edged swords that are well regulated in western countries, but is not in other parts of the world.