The iPhone app store is Apple's beachhead into mobile computing in general, the iPhone the first of many such mobile platforms. App store developers get rich, a

The iPhone app store is Apple's beachhead into mobile computing in general, the iPhone the first of many such mobile platforms. App store developers get rich, and Apple's platform becomes more popular and attractive to users. It has worked well so far. Microsoft already owns the majority of the desktop space. Why would it need an App store? The returns on investment would be insufficient to justify any investment.