How important is sidespin?
You know the ones: the ridiculous banana-shots the Nadal pulls off on the run or, more commonly, pros get on the slice backhand.
I was arguing with a friend about how important sidespin is. He argued that it is sidespin on the forehand can add an element of variety and can add a margin of error to already-difficult passing shots. Sidespin on the slice means that there is another factor for the opponent to deal with and the ball is less able to be hit away.
I believed that sidespin is a gimmick and impractical. I hit with a lot of topspin and can get spidespin if I try, but it adds little to the shot. Sidespin on passing shots is extremely difficult in practice and actually makes it harder to get the ball in, because it is hard to know where it is going. On the slice, sidespin can be helpful, but can easily cause excess lurching that will send the ball floating out.
TL;DR How helpful is sidespin? Do you guys find uses for it?