There are a lot of good reasons for pruning plants and most are for fairly practical objectives. During Autumn for instance we remove between a third to a half of the top growth from shrubs like Buddleja or bush Roses to help prevent 'wind - rock' problems. A more severe prune follows this in the spring and you may wonder why this pruning isn't just done in one go now. The reason is that if hard pruning were carried out now, a mild spell could result in new tender growth developing, only to be hit by severe winter frosts with potentially fatal results to the plant.
Sometimes however, pruning can be carried out for purely aesthetic reasons where you are simply pruning for effect. For example, there are many shrubs that grow as a simple bush shape with the lower branches and stems growing right down to ground level, which is fine in most situations, as this is their natural shape.
Sometimes though, it can be desirable to remove some of these lower branches in order to open up the bottom of the shrub. This is particularly useful where they are planted in the centre of a lawn. Here, opening up the lower part of the shrub can unblock the vista allowing other parts of the garden to be seen and can also expose the trunk of the tree or shrub, which can be very attractive on some plants.
I have had particular success with this with Magnolia bushes and also a huge Portuguese Laurel, which originally looked like a colossal blob in the middle of a lawn. However, after removing the lower branches and 'lifting the crown' of the bush then looked like a stately tree and has now become the focal point of the garden.
Opening up the shrub not only exposes the beautiful bark but can also reveal wonderful shapes as multi stemmed shrubs have several trunks that twist and turn, quite artistically looking superb when silhouetted or given up-lighting on a winter's night.