My reading is that they're worried about their explosive GDP growth leveling out and the political instability a debt crisis might cause.
"credit system" is far less established than countries like US, and private companies are generally much less trusted by the government and by the people (which is the opposite to the US). Some big private companies like Alibaba has started to create credit systems themselves, but the state owned banks and law enforcement would only use something backed by the government.
The "social credit system" it actually not that different from other credit systems excepted it is managed by government. It's really needed now given that there was a rising debt default problem -> Without a credit system, many people thought they can just delete the app where they borrowed money and get away with it. It became a crisis when a lot of this happened at the same time.
Surveillance is a separate topic. It's one of the technology advances that made law enforcement easier (like DNA samples are much more used nowadays in identifying criminals). There has been reports that criminals being captured with these new tools. It's something that western people fears a lot, so all the western reports focuses on the negative side of it and exaggerate it many times more.
But if you were opposed and spoke out, you would be punished, so why should we trust you to be saying what you really believe?
But even if what you say is true, it means that that speaking out has no impact on governmental policy, since if you start to have influence on the public you get shut up. And if that is the case, why should anyone ever bother to speak out.
Why don't you just admit it, you like living in a dictatorship.
If you want to watch for change in behavior - increasing or reducing of oppression - in the Chinese system, look at consequences and restrictions (ie applied action derived from their policing systems), rather than things like surveillance broadly. They will always max out surveillence and awareness where they can (the people de facto have no rights, so these things are not viewed as abuses of existing rights), short of becoming a liberal Western-style democracy (which isn't going to happen). The consequences and oppression/restrictions will change depending on the regime's aims, that's where you can best judge the nature of a given government that is in power.
To use a classic surveillence example - the US Government during the Hoover era didn't voluntarily restrict its reach. They were heavily limited by the technology of the day in what they could do. As technological limitations lifted, the expansion of surveillence leapt forward accordingly. Nothing actually changed, Hoover would have been doing what the NSA is doing today, if he had the technology back then.