You keep saying communism, but this is about socialism. So basically, yeah, you missed the entire message... They could say Socialism inevitably leads to Communism which is irrelevant to this topic and I don't necessarily believe.
That said, your entire rant is about a completely different subject, Communism. Which is in fact, not Socialism.
Also, if you had finished the game, you would see it does revert back to Capitalism in the end. Once you've managed to change all of the pieces of Society to Socialism the everything begins to shift back. Because in order to change everything you have to juggle certain policies, you can't have them all. But with a tedious balancing act, you can achieve Utopia. Once the person or peoples tirelessly balancing everything get tired, or become complacent with the benefits of their utopia (The player does nothing because there is nothing to do). The policies begin to shift back, either due to greed or some other force, which in turn reverts the entire city back to Capitalism.
I think the point of the game is to show that a utopian society is possible with Socialism, but it is a tireless effort and people will inevitably become complacent once "perfection" is achieved and the "greed of men" will seep back into society and slowly revert everything back to capitalism.