Tue 11-Jan-11 02:31 AM | edited Tue 11-Jan-11 02:33 AM by pwarbeck
Camera sharpening is global capture sharpening. As you say, for many images it's good enough. But with with camera sharpening, you can only control intensity. For these reasons (global, limited control), it is often recommended to do capture sharpening as an adjustment step.
Using USM, you have control over radius and threshold as well as intensity. When done as an adjustment step, it is possible to sharpen selectively. For example, if you sharpen in order to bring out fine detail in foliage, then foliage lying against the sky may exhibit halos. Drop a minus selection control point in the sky and the halos disappear. Or, if sharpening creates noise in the sky, sharpen the sky selectively with a high threshold. Both of these are examples of selective capture sharpening. We choose to do them when global camera sharpening is not good enough. I would not call either creative sharpening.