I agree that Quidditch is mostly very poorly though out in terms of tension, but there is some strategy into the Snitch that the films fail to properly explain. Yes, catching a Snitch ends a game, but the common misconception is that it's an automatic win. Actually, you just get 150 points, and often that's enough to get you a win if you catch it early enough in the match, but if the other team has already scored 160 points from the Quaffle and your team's score is still 0, then by catching the Snitch you are essentially forfeiting.