I don't think it's true that users generally want things to be file-centric instead of app-centric. Sometimes yes, sometimes no. The underlying lack of data integration between apps - even simple copy and paste can't be relied on - is a bigger stumbling block. It's also odd that the screen-layout and I/O limitations don't feature more prominently. The author's larger point - that you don't have to spend so much effort telling people something is useful if it really is - rings true, but I'm not sure they make a very good case for it.