The Store isn't for income
Not having 'developed' anything since before Windows 95, I have no idea what challenges there might be in ARM/win8 RT software. My hunch is that the whole ARM concept is a mistake, that having the familiar to build on is more important, and much harder to get around, than battery technology. And I myself just don't want computation following me around. I mean it's anywhere I spend much time or I won't go there; I hate travel in principle but if I am walking by choice, it's to talk and to look, not to futz with some contraption (on other modes of travel I find either books or daydreams preferable). I only have a cell phone because my ISP is less reliable than my old landline and payphones are rare, working ones rarer, and affordable working ones, nonexistent – and the landline would cost me more than the cell and almost as much as the ISP. I don't WANT people or information reaching out and touching me!
Yet the tablet IS important simply because its use is part of making one's connections to work, to people, to places, and to goods/services place-independent and portable (I'm cool with place independent, lol). If Win 8 Surface_Pro works as intended rather than as the review says windows RT Surface_plain, it will address a real market. People do different things portably than sitting at home or at a fixed workplace; I can't imagine using Access on a city bus.
The STORE: I think it was the combo of seeing people actually like or at least tolerate the thing that was the key. Maybe it's just easy, maybe it's more secure, maybe the choices being sorted by authority pleases some people, maybe the lack of channel partners makes it more efficient but probably all of those to some extent. The reason it makes money is people WANT the contraptions and enough of the APS in the store, to buy the contraptions in huge numbers. The first mover tends to win when a new niche is found and especially if the same outfit gets to ride the wave, should the niche develop into a major market all by itself.
Eventually all dominators have competition. Sooner or later some combination of wanting to preserve all that wealth, please late-coming stakeholders, and the end of the ‘cosmic inflation’ phase, leads to conservatism and bureaucracy. Others will offer things that seem to be the same, are somewhat interchangeable with the originals, but do more for less faster and flashier. Then someone will throw in something new, as in a human need not previously addressed by the old stuff, possible by never-before-seen concepts and technologies. Then the next new niche and the next new tsunami will start somewhere else.