How can using a stylus address a sensitive surface of the device? 

A stylus is going to vary in terms of the usefulness depending on the person and their preferences, although maybe in some situations, a stylus might work out better than in another situation. I do think that, with more innovation we're finding better solutions. Things as simple as scrolling might be a solution that becomes second nature to most people. There are hundreds of different tools available, there's hundreds of applications for those tools, and there are even more solutions being invented every day. A hybrid of different approaches and a combination of technologies and configurability of experiences is what is going to provide for greater ease of access to a wider range of people.