1) Why aren't most high-end Android tablets selling well? Because they lack features that distinguish them against the iPad and function primarily as fun, niche devices, which makes the $500 price point unattractive to many people.
2) Why are the ASUS Transformer tablets (original and Prime) in fairly high demand? Because they have a distinguishing feature, the integrated but detachable keyboard, which greatly broadens its functionality and makes it much easier to do content creation on a tablet, while still having a "fun" device.
3) When is content creation important? When one needs to do work, like creating documents, spreadsheets or the like.
4) What is the dominant software package for doing work-related activities? Microsoft Office.
5) What is the operating system most people use when using Microsoft Office products? Windows OS.
6) What will be the Windows OS that will (or at least try to) be optimized for a touch-screen interface but still allow access to Microsoft Office products? Windows 8.