Well, sadly it isn't as simple as restoring a old UI, as the new UI was built from the begining specifically for touch devices. Even Apple recognised that a tablet OS and a desktop OS are two different things (although there is more commonality then there used to be)
As for Office (2007 onwards) that is an even more ammusing story, which probably holds some understanding as to why Windows 8 is the way it is.
Story goes that after Office 2003 was released MS asked a lot of their customers what they wanted to see in the next version of Office. A large portion of what was suggested already existed. MS's takeaway was that the current menu system was to complex and they introduced the ribbon to simplify the interface. My takeawy is that most Office users use it for basic tasks only
Given what MS did with the Start screen in Win 8, I have no trouble believing that. Perhaps MS need to do a little more research into the people who are currently using thier products instead of purely focusing on the new aspects.