1) I think you missed my point. I wasn't talking about the relative merits of LibreOffice versus MS Office (and frankly, I think you are vastly overstating LibreOffice's merits). I was talking LibreOffice's ability to read and write Microsoft Office documents without error. Document format compatibility with windows is so important that (IMO) anything less than complete fidelity to windows is a failure. Because it means that huge swaths of the marketplace -- pretty much anyone who has to interact with someone else who uses windows -- will avoid using LibreOffice because they can't take the risk that their boss/teacher/co-workers won't be able to read their documents.
3) I haven't used Windows 8, but I'm willing to bet it's trivially easy to enable the start menu. The same cannot be said for disabling Unity and switching to something else.
4) If a user doesn't need to do much more than email, web browsing, and instant messaging, he can probably get everything he needs from the repos. But I'm willing to bet there's a lot of people out there who have at least one app that's not in the repos, or for which the repos have an out-of-date copy (Mediawiki, just to name one) And then Linux becomes a usability disaster.
5) Again, you missed the point. The lack of standardization in everything from package managers (Yum/apt-get) to desktop interfaces (Gnome/KDE/Unity) means that anytime a user encounters a problem and googles it, if he finds an answer at all, there's a pretty good chance that it apply to him because it pertains to a different distro/app. It also substantially increases the learning curve for any newbie and adds artificial barriers for experienced users to switch between distros. And there's no technical reason at all why this should be the case.