I do agree that Windows 8 is being targeted pretty hard on younger people, if they're three years old, so be it!
I loved 7 when it came out, as it was a GOD send and my goal was to obliterate any system running vista and replace with 7. But 8, WHOA! This is something beyond 7.
Having said that, the release of 8 is a different time than 7. People have newer PCs, with real decent hardware. They also have an OS that isn't like the previous one where the only thing it could do was to look shiny and pretty when everything stops responding or having to wait for something to load.
But, unlike the year 2009, lots of people nowadays are buying phablets thinking they can replace their Windows 7 PC and realizing they can't due to the fundamental fact that those devices are NEUTERED SMARTPHONE OPERATING SYSTEMS! Blasphemy to say that an ipad is a PC! Seeing the new developments with tablet PCs and the capabilities and possibilities they have, Windows 8 could do well. I personally don't see it being hugely adopted for a while. It might not be due to the new UI, it could be. I might be more that people are satisfied with what they got already.
I see a similarity with Windows 8 and Windows Phone, people need to physically themselves to see what can be delivered.