IMO, Russia doesn't want to demolish Kiev but instead use the threat of demolishing it as a potent bargaining chip in upcomming peace negotiations . And besides the Russian people regard Kiev as a Russian City and they will want it spared just as the French wanted Paris spared during WW2.
Kiev: "The city is still considered a sacred place for all Orthodox Christians in Russia and Ukraine.It was also the first capital of the Russian State, which at that time was known as Kiev Russ.." (source: justgorussia.com)
