The engineers were good (if not too good, it all still stands...), but they were limited by the ideology. The city planning and the architecture were at the ideology's service. For instance, rarely did buildings have ground-level spaces for commerce and services; after all, any form of entrepreneurship was discouraged by the economic system, so there was no official need for cafes at every corner. The streets were made wide to allow for easy troops transfer and make it harder for any rebels to create barricades. Some streets were shifted by a few meters to obscure a view of churches and other historic landmarks which could provoke unrighteous thinking.

I heartily recommend Ryszard Kapuscinski's 'Imperium' (it's available in English) if you want to learn more about the Soviet Union in general and different cultures inhabiting it at the time. A lot of spot-on analysis of how the system worked. Brilliant documentary writing, too.