Thanks! :)

It was the high vantage point that prevented the lens from creating "bokeh" (blur). If I could've shot it from lower, the lens would have naturally created some blur in the background, as the cygnets were quite close to me.

In this case it worked nicely, the surface of water isn't distracting so it generally acts as a good background for photos.

The idea with the blurring is actually to hide distractions behind the object you are shooting. If the background is very busy, you would want to have the blur instead of the actual background. The blur that you create by opening the aperture of the lens is a useful tool in those cases.