The "ecosystem" is the users, customers, OEMs, component fabricators, OS producers, application development houses and IT professionals who advise, install, train and fix things that go wrong. It includes you me and this forum, our children and the developing economies of the rapidly changing 3rd world.
Much as many folk hate to admit it, Microsoft is the driving force behind the computer industry (the energy that powers the ecosystem) and has been since the early 90s. In this way you are right to say Microsoft is the critical element in the ecosystem, and Microsoft would not exist but for its customers.
Microsoft is a victim of its own success with XP, and is determined that it will not create another Frankenstein's monster that will not die, yet out-competes all its younger stablemates with sheer tenacity, and reinforces a perceptual model that is intimately tied to the desktop and start menu that most users have grown up with, and find so hard to give up with Windows 8.
By having a large proportion of Microsoft customers not actually paying money to Microsoft any longer, Microsoft loses money, without losing market share. That threatens the whole computer industry with stagnation. The hardware and component manufacturers also want to continue innovation instead of folding or shrinking through lack of sales.
In order to break the mould, the current strategy with with Windows 8/8.1 has been to
make the system incompatible with older hardware - whether this is a terrible mistake, time will tell. Microsoft is after all making a major foray into manufacturing its own hardware on three fronts - Gaming, Phones, and Mobile Computing, and wants a single codebase for all flavours of its products. That keeps prices down, in theory.
Microsoft does not force you to change your car for a newer model, even if it still is running well after 10 years of daily use. Nor your TV, mobile phone, GPS or curtains. You change these things because you want new ones, or at least, newer ones than you currently use. Microsoft also does not force you to stop running your Windows 7 or XP machines, but it will not run Windows 7 on a 486SX2/66 with 8MB RAM either. Just as there are people still running Windows 98 to control industrial equipment today, there will still be people running XP and Windows 7 ten years in the future. Microsoft just will not support these users, and neither will the hardware manufactured in 2023.
It has parallels with the fashion industry - nobody wants last years colours and styles. I'd bet that nobody blames a couturier for making a fashion-conscious someone throw out her old wardrobe.
The problem with Microsoft, and the perception it creates, is the near monopoly it has in business and home computing. As far as PCs are concerned, Microsoft "owns" the hardware manufacturers. That gives Microsoft the mandate to dictate future developments in computing, and since it wants to extend into parallel markets of phone and mobile computing, to decide what hardware is going to be compatible.
An environment of trust is laid down in some rules like Product Lifecycle, EULAs, and commitment to support, fix bugs and problems, and for the product to perform as specified. For that trust you pay for a license to use the product in a certain way in compliance with those rules. Believe it or not, you do have consumer rights and can return your license back to Microsoft for a refund if the product does not work as reasonably expected.
Neither are you committed to send your used hardware for landfill. Your state legislature is committed to increasing recycling of Electronics
Guidance for the Texas Recycles Computers Program and there are programs for recycling computers in place
Texas Recycles Computers Program.
What may be obsolete to a user who wants the latest OS on their system may be the best ever gift to a child who has been raised in relative educational poverty. A computer with an internet connection in a village in certain parts of the world compares to having a new public library in your town 100 or so years ago. Don't forget that charities help underprivileged people at home and overseas, where your working but dated computer and OEM or upgraded software will get an extended lease of life and help educate children to live richer lives in the 21st century. Microsoft and the Gates Foundation itself is noted for the charitable works it does globally.