If you think that having a real alternative to Office is a minor point, than you haven't worked in a corporate environment, and I'm not talking about Internet companies, but traditional medium-sized engineering companies, accounting, legal studios, government agencies etc...
Millions of professionals very good at their jobs, but with no particular technical proficiency, have been using Word and Excel for years, and convincing them to switch to something else would take much more effort that any IT manager with a budget can possibly muster.
Moving the entire world's manufacturing processes is not a "little thing to change". Same thing with Active Directory - millions of people work through this system, it's no small task to transition them to something else.
It's not doomed as a consumer OS. People want to use the same OS at home that they do at work, it feels familiar to them and they already know how to get stuff done.
However, I do see it as a possibility that windows being doomed as a consumer OS might happen in our lifetime. As more things move to service oriented and more devices become connected it's very plausible that the majority drop their desktops and laptops and rely on mobile and chrombook level devices.