What makes Crimea important is it’s rather large Russian population and it has highly developed seaports that were constructed in the Soviet Union. In Russia’s eyes not only is Crimea ethnically Russian but Russia has already invested a lot of money in it for its own protection. Right now Russia is extremely anxious and nervous due to NATO making bold moves with Missile defense systems which should’ve been a thing of history after the Soviet Union collapsed. Russia sees NATO-American interference in the region as a blatant provocation and renewal of the Cold War. The whole point of Russian influence in Eastern Europe (just as with the Warsaw Pact) isn’t ideological insomuch as practical since the West is Russia’s most exposed front from which Russia has nearly capitulated in history.