First off, please break up your points. The wall of text like this simply makes people want to ignore it.

Secondly, the statement, "(Microsoft's) reputation is only getting better among consumers..." goes counter to the direction consumers are going--apparently headed towards OS X and iOS--in other words, Apple. Analysts have put Windows as low as 55% in overall web hits on sites when compared with desktop and mobile OSes combined, with iOS making the biggest single hit against it.

Windows 8 is still fighting strong resistance by IT and techies mostly due to the (formerly known as ) Metro UI. Microsoft has to fight that resistance because if they don't put forward a strong mobile platform, Windows itself--Microsoft's core platform--will simply be replaced by other, more forward-looking operating systems. Not only is Apple making strong inroads into traditionally Microsoft environments, but Linux--in several forms--is starting to do the same.
Because of this, the OEMs really could care less whether Windows lives or dies. They needed Windows to survive previously as ever prior attempt to push Linux of any flavor fell flat on the desktop market and Apple's OSes simply can't and won't support third-party hardware by intent. Those OEMs effectively destroyed Windows' reputation 25 years ago but Microsoft's penetration of the enterprise kept it alive by sheer inertia. Until now. With iOS's invasion of the enterprise, OS X is making inroads and proving that it is just as productive as Windows--if not more so.

Yes, you are right that Microsoft really needs to lead this drive; as I stated up front the only reason I saw this is that I did bother to read through that wall of text. All the OEMs have pretty much resisted change with the exception of HP which has tried for 5 years or more to support Microsoft's touch paradigm. Little good it did either one. But the OEMs aren't the only ones at fault and that's something I've been saying for almost as many years as there have been "tablet PCs". Without supporting software, a different interface simply isn't going to make it. Software developers then are the ones who have really sunk the boat.

Could the industry stand to lose some OEMs? Personally, they should have a long time ago. $200, $400, even $600 PCs were mostly made up of second-hand or second-grade parts that might or might not work reliably for any period of time. I've seen examples of these low-end PCs not even survive the unboxing or, if they did work, fail--sometimes more than once--within their 90-day initial warranty. (An example is an HP Compaq purchased for my father-in-law that died in its first week, was sent out for repair and returned within the first month and died again--requiring a motherboard replacement less than a month later. You get what you pay for and if you pay nothing, you get nothing.

Microsoft, by creating and marketing Surface as its own product, has a chance to break the old chains and play by Apple's rules--control every aspect of the product from the OS to the hardware. The OS is only as good as the hardware running it and that is why Apple is suddenly moving forward (its market share has grown almost 10x in just 5 years) while Windows is fading fast. Microsoft HAS to break that pattern and only by completely changing the playing field are they going to retain even a semblance of their old market dominance. With luck they'll slow that slide but they may never regain what they've already lost.