That's a failed statement to claim that the current marketshare is your measure of success. Its 90% today but what about tomorrow? Next month? Next Year? Marketshare is meaningless if your product development is on a decline. Windows 7 was a big up for Microsoft, where they actually put in the manpower to make it great. They have however had enough flops to rub people the wrong way. Nobody gets excited for a new Windows OS or Zune or Microsoft Store. Thats for a few reasons. 1. They have a history of failure, 2. They have horrid marketing to promote their image, 3. They don't change enough in a new product to create excitement.
They have created a huge fan base for the Xbox but what now? They fired the development team so who takes the reigns from them?
Microsoft has the same problem as RIM, HP etc. They coast through the years on the coat tails of their own previous products and put no time into R&D. They are now in the stage of paying for that mistake and scrambling to push out crap to stay above water. This isn't rocket science. Its common sense from a consumer's perspective.