I am not a Microsoft fan (search my comments) but I am a HUGE Metro/Modern/RT/Windows Store App fan. I agree with MS that the real-world metaphors shoehorned onto computers have limited their usefulness and I LOVE the total embrace of Fitt's Law.
Windows app developers choosing closed source doesn't have anything to do with Microsoft any more than Mac app developers choosing closed source has to do with Apple. Both Microsoft and Apple contribute a large amount to open source projects themselves.
Windows RT runs on x86 and x64 in addition to ARM. ARM has everything to do with energy consumption. Intel is just not getting there with x86/x64. The future is battery powered and frankly, Intel needs the competition of ARM to get them moving even if ARM can't touch raw performance of x86/x64.
If people didn't care so deeply about MS Office there wouldn't be an OpenOffice or an iWork. It's also asinine to insist that only Office keeps people on Windows. Intensely extensive hardware support, Exchange, Active Directory and many other things that other operating systems don't even try to compete with are also MASSIVE factors.
Windows on ARM already had an "ecosystem" it's called Windows. USB has delivered on its promise. Bluetooth has delivered on its promise. This is not Android, iOS world where connecting anything other than a memory card is both frowned upon and difficult/expensive.
I will give you that Windows Phone 7 was a failure by all accounts. I have an HTC Titan that I love and I am crushed that it will not receive proper system software support but I understand why Microsoft did it. There is a level of hardware features that every WP device must have, in both WP7 and 8. This lets Microsoft declare things like taking pictures on Windows Phone is both faster and easier and not mean "just the Nexus Windows Phone". Live tiles blow notifications and most widgets away in my opinion and you can search my posts on XDA under Dragon_76 to see how long and extensively I have used Android (I had a G1 and left Android Phones at Moto Atrix).
Windows 8 is going to make everyone ask why Apple didn't do the same thing with Mac OS/iOS.