How about tweak the thinking a bit: What's in there for China to totally embraced democracy? Will it become an advantage for the country (Or the leading elites at least), guaranteed? What if the change has failed and lead to something worse?
There are risk factors, and people don't like to take risks. Which is why societal changes are more likely to occur during crisis and disasters, because people simply have nothing to lose anymore.
For CCP, the "Take half the cake" approach is less risky for them, so they did that, and now everybody see what's happened after.