Government workers produce fake social media outside of China too. Public opinion outside of China is very important for business and strategy.

Present China as an improving progressive regime, smooth over its human rights problems, and china can gain more influence internationally. If you are dealing with China, keeping one eye closed can be very profitable.

The UK gave Hong Kong back to China, regardless of what people living in Hong Kong wanted. They are now heavily mutually invested underwriting loans for nuclear powerplants: http://www.bbc.co.uk/news/uk-england-somerset-34306997

In case of invasion, this kind of thing makes a big difference. Invasion aside it continues to shape Taiwans influence - why do you think Taiwan is not a UN member state and China is?