I think it's a bit insane to think that Russia couldn't completely and totally obliterate civilian central infrastructure in Ukraine if it wanted to. It's not like these locations are hidden or top-secret, or like Ukraine has the ability to completely and inevitably stop the attacks.

However, whatever wins this achieved would probably instantly be overshadowed by the negatives. Think of mass famine, relocation, refugee-ism, ... Not to mention a destroyed infrastructure that the eventual owner needs to rebuild as a first priority. Not even to mention the increased levels of international condemnation due to such a targeted attack on a civilian population.