Tactile feedback gives us a rich and visceral way to experience our environment. It allows us to discern things such as shape, texture, volume, density, and relationships between objects.
Current use of tactile stimuli in touch screen devices is primarily addressed through vibration. Research has also produced surfaces that are able to physically distort a screen. It’s not unreasonable to think that touch screen devices might one day be able to mimic more complex and subtle surface texture.
Meaning is ultimately determined by context. The meaning of one thing is determined by its relationship to other things. This is the same principle we employ when we organize visual information on a screen. We use elements like white space, color, alignment, grouping, and hierarchy to draw attention and give meaning to elements and sets of information. The use of texture on a touch screen device could provide users another facet of understanding and context.
Touch could make information more accessible on surface devices. A sight impaired user might be able to complete a task through touch alone. Tactile qualities could also be used to support visual elements, skeuomorphic or not.
The possibilities for tactile feedback on touch screen devices are likely as varied and nuanced as the tasks themselves. Of course, each implementation would have to be considered within its own needs and design constraints, just like any other smart design element.