Countries that get the contest more seriously have greater chances of winning and deserve the victory more. There is nothing strange in that. As a confirmation, Serbia celebrated the victory like this:
(EDIT: Sorry, I am too dumb for your Youtube command, it didn't work out)
Losers have the right to cry...
Yes, block voting does exist, it has always existed (even before the East was included). But the way most of Western Europe defines the blocks is a complete nonsense. "If you were communist then you are on the East, otherwise you are on the West". So, for example, Greece is on the West! In reality, however, the things are different, and I can count at least four blocks: East, Southeast, North, West. Yes, East and Southeast, both classified in "Eastern block", traditionally don't give many points to each other. Who receives most points from outside its own block wins, so Serbia is a rightful winner. But how Ukraine (which I found totally unfunny, even Romania was funnier) and some other countries deserved to end up in top 10 I really have no clue...