Digital Frame is an excellent filter that does many things. However:
With many aspect ratios, it is impossible to set the width size of the mat to the same size of the mat height. The user should be able to disconnect the mat-frame ratio for individual adjustment of both mat and frame. (In the image here, the unequal sizes of height and width in the mat are distracting, in my opinion.) Palette Knife and Oil II with Digital Frame
Not everyone wants a frame that looks like a wall hanging. For viewing online, some would prefer a less obtrusive/smaller frame/border such as those available in the old Topaz Adjust and Topaz B&W Effects plugins.