Well don't forget that rugby is played 'down the line' and at the end of the line stands the winger! They are in theory one of the quickest and most dynamic players, able to break away towards the end of the line and ultimately...score tries!
If you're rubbish you'll spend the whole game watching. If you're good your team will get the ball to you. Good wingers score tries because they have space and the speed to use it..
It's the same as football basically why is there a wing there? To spread the play out and score tries by running down the side of the pitch using their speed And also to tackle because the opposition will be also trying to run down that wing.
The same point as any other position on the team.....tackle and try to score!
No worse than fielder in cricket.
