Who cares if Windows 8 is a dog. Vista was a dog and it led directly to 7. Give some credit to a company that could sit on it's old style of business like IBM in the late 70's, but instead challenges itself with products which can fail and are interesting and different.
Microsoft cares if Windows 8 is a dog. They're betting the farm on this release. They desperately need this to work as a gateway to the mobile space, an area they're hopelessly behind in, and they don't have another couple of years to get it right.
Apple's actually made a number of very significant improvements to OS X over the last 10 years but they also recognized the UI paradigm is fundamentally sound for the desktop space so there's no reason to make radical changes. Of course they also realize that an OS is not a one-size-fits-all product.
2. The message is oddly mixed regarding Microsoft itself. The idea is that there's some new stuff on the horizon that will solve all the problems the current stuff has. Why pay to advertise that your current stuff has problems?
Maybe you should ask the John McCain
This restaurant was advertising breakfast any time. So I ordered french toast in the renaissance. - Steven Wright, comedian