I think you are missing the point. It's Crimeans that wanted to go back to Russia for a long-long time. Russia just seized the opportunity and made it happen, before the war.
Crimea has lots of problems but what is certain - Crimians do not want to go back to Ukraine. And Kiev just wants to punish regular people for that, applying master-slave mentality here: closing borders, cutting water, trying to cut electricity and all this with European and American leaders turning a blind eye.