I agreed with pretty much your whole post there, but you're wrong on some of the MS stuff.
First: NTFS is pretty good (I'd say better than apple's HFS). IE is pretty good these days too - not the best by a long way, but "good enough" and a long, long way from the bad old days of IE6. Windows hasn't been based on DOS since windows 98 (I'll ignore ME, too many bad memories). The base windows for tablets is likely quite different from the desktop version anyway. So basically none of the reasons you've given for it being bad are really valid - I'd say the back end and base of windows is pretty good these days, and most people are reasonably happy with it.
The real problem is this: They're mixing a tablet and desktop OS, and forcing desktop users to live with it. If you have a nice workstation and a keyboard + mouse, you're expected to use a touchscreen UI with huge buttons and squares everywhere. It's a huge step backwards for regular PC users in a lot of ways.
On tablets (the ARM based ones at least) there will be no windows desktop - only metro. Metro is pretty decent, so that's OK - we'll have to see how it works out, but in theory at least the windows 8 tablets could be pretty good, and serious competition for apple.
And there's a massive amount of windows software available already of course! No, wait. There isn't - in fact there's hardly any software available because metro is pretty much a new OS. Software will need re-writing for it, UIs will have to be redesigned, it's a lot of work for developers. Will they put that work in? A lot will see if it takes off first, because it's a new platform that's very late to the market. It starts with 0% market share, and that's not an appealing figure for developers. And that's exactly the same position Windows Phone 7 is in. Late to market, pretty good, but largely ignored by devs because it has no market share, and largely ignored by customers because it has no market share and very few apps.
So, you have a tablet that has a big uphill struggle when it enters the market, and you have a desktop OS that will be less productive because it's not really designed for desktop use. That's the problem with it.
MS really need Windows 8 to fly - they're coming under pressure from the mac on the desktop, and the desktop market itself is under pressure from tablets. They have a shrinking percentage of a shrinking market. They need to win that market back, and they need to start dominating the new tablet market or windows will end up disappearing.