Windows 8 sales haven’t been doing any better than Vista did when it was introduced back in 2007. (Vista never did live up to Microsoft’s hopes, as users responded to its introduction with a number of pointed comments, like “Huh?”) Windows 7 was created to solve the problems of Vista. Someday there will be a Windows 9 to correct the problems of Windows 8.
This whole process is an extremely clever marketing plan to see how often a giant company can screw up a new product, and then charge the user for a newer new product that fixes the previous product. (Remember the Golden Rule: Never buy anything with a low serial number.)