Shoulda coulda. What should have happened is NATO busting the door to Russia the second they crossed the border. In reality, Ukraine is in a weaker position geopolitically. They are clawing their way up the totem pole though. Same reason why WW2 ended on such shitty terms for everyone in central Europe - Russians were in a stronger geopolitical position and could dictate what they wanted. The one that wants peace will always back down from using force. The one who wins is the one not afraid of war or its continuation.
So many targets that are way more impactful than civilians. Russias economy is one of raw materials. Processing them is done by very large vulnerable manufacturing plants.
The psychological impact of Moscow being bombed would help fuck with the Russians. Plus there are plenty of military assets in Moscow still even ignoring rails.