Stupidity comes to mind, they must have a finite supply of missiles to use, so as long as they are firing them into high rise buildings they are not diminishing the Countries military capability to defend themselves and fight back, the tragedy in it all is the innocents getting killed or maimed as Russia attempts to demoralise the Ukrainian people and break down their spirit and resolve.
According to the ISW they have estimated that Russia has used 70% of their cruise missile stocks.