Not all the creatures that live in the garden are welcome by gardeners, many don't like to have slugs around as they eat the new shoots on plants and are seen as a menace.
As the area around my pond is left to be as natural looking as possible I don't mind them being around and the damp conditions around the waterfall makes a good habitat for them. It's strange that people don't like slugs but are more inclined to snails, basically a slug with it's own house.