I think the windows 8 / metro / startmenu thing is like the windows media center but in reverse.
Microsoft said more or less "not many folks use media center the stats show us this fact" but in the last 2 versions of WMC very little has been done to promote it. it's a "Hidden feature" that i bet 70-90 % of users have never even seen and even if they have seen it very few of them have a cable card slot to get use of one of the key features .. or a tuner card for that matter. so now it's going to be an addon for windows 8.
I rather suspect that the folks at MS have a fear that if they did not push metro it would not take off and go mainstream and wind up like WMC soon down the road.
so they "bet the farm" on it.
problem is that for a can't even begin to count how many users the new metro start screen will be a deal breaker as it stands now with forcing it on users.
IMHO they should have just done two versions of windows and let folks pick the one they want.
if metro and the tablet are as great as they think they are the market would show this with the sales numbers.... that's a really good "stat" to go by.
there are problems with the two versions idea yes, but I see problems with the "all in one" method also.
I disagree with your conclusion and I think your conclusion contradicts the first portion of your comment.
I look at the Office Ribbon. I think (as does Microsoft) that the ribbon UI is hands-down superior to the old Office UI, But if Microsoft had given folks the option of turning off the ribbon so they could use the old UI instead (an option that many folks demanded before Office2k7 RTMed), then lots of folks would've chosen to stay with the old Office UI, not because it's better than the new ribbon UI, but out of force of habit or fear of change. "Letting the market decide" by allowing an option to turn off the ribbon would've been stupid, because the inferior UI might've won out based on habit and/or fear. So Office would be stuck with the old UI forevermore.
It would've been very sad for Microsoft to spend lots of time and money on developing the Office Ribbon, then get scared and offer users the ability to use the old menu-based UI, and see everyone pick the old UI out of habit or fear, so that the clearly better ribbon UI fades into oblivion, never being given a true chance to gain traction.