It's the Ecosystem, Stupid
Marco Arment on the iPad and would-be participants in the market for tablets:
To be competitive, a newcomer to the tablet software market needs to replicate or sidestep the need for nearly all of Appleās major efforts, including synchronization of media and data with Windows PCs and Macs, integration with popular web services, an integrated payment system that customers will actually use at a reasonable rate, a well-stocked music and video storefront, plenty of high-quality third-party apps and fun games, a sophisticated SDK and development environment, widespread retail availability and customer support, and an assortment of good first- and third-party accessories to fulfill common needs (cases, chargers, docks, screen protectors, extended batteries) and give the device new uses (tripods, speakers, styluses, input and output adapters, wall and car mounts).
I think Marco’s point is great, but stops too short, it’s not just the iPad. The tablet needs to work with the phone too. People seem to want to buy an app like Instapaper once as a universal app and have it run on both their iPhone and iPad. How would that happen across device platforms? People used to be worried about DRM tying iPod users to Apple through their iTunes purchases, but the “iOS X” ecosystem is so much more expansive. Countless bits entwine across devices to make an increasingly seamless experience. A fully Apple-less solution, cobbled together from a many headed hydra of Google, Android vendors, PC makers, netbook makers, and Microsoft, seems like a pointless exercise if not a Sisyphean challenge.