There are things Metro can't do that the start menu could. The desktop experience of Windows 7 revolves around the Start menu, which doesn't exist in Win8.
This is not progress
I understand a lot of people are fine with a simplified tablet UI for a launcher. That is great, but at least be honest with what it is. Very little of Metro is conducive to a desktop environment. I hope you like scrolling horizontally. Luckily the search works in a similar manner to Win7, but they still have some hoops, your search is filtered by type, whether you want it that way or not.
This is purely a strategy to get a larger user base for Metro to drive development in MS's new walled garden.