i'm very iffy on that topic, on one hand i think it shows competitiveness but like Roy said, it also shows lack of sportsmanship and class.
I think this is where I stand
during the series, after the game is over, I'm probably fine with not shaking hands with an opponent, you're still at war with each other
but after the series is over, shake their hands, it's over, just say, good series, we'll see you guys next year and move on, war's over