You somehow forget the say the Ukrainian people have in all of this. I think that they made it clear what they think after Yanukowitch announced that he will back off from EU trade talks and will join the Russian economic union.
Using your logic my country would be still bound by the Yalta agreement and would remain a corrupt hellhole run by communists.
And don’t tell me what I would or not would fight for. I would not go to Afghanistan, but defending Tallinn against he Russian hordes is something I would very much be ready to do. Because I understand that it is better for my family if I fight in Tallinn today than in Prague tomorrow.