That might have been true 10 years ago, however today there are plenty of flavors that are very easy and default install just fine with little or no interaction from the user.
The main stumbling block is install base and compatibility. Windows has as big a strangle hold than ever. Apple has made some strides, however with their expensive machines, they will only ever be niche players. Where they have been loosing and where it may transition into a loss for them is the tablet and phone markets which are all basically iOS and Linux (in Android). If computing transitions along those lines, windows will eventually lose. Which I am sure why they made the ill conceived leap with Windows 8 and the Metro interface to try and get ahead of any convergence that may take place in the future.
The issue with today is that they have such a large install base that is not compatible with linux. I presume that is why Red Hat bought WordPerfect software back in the day, as it was the only one that challenged MS on their home office turf. Problem was it was too little too late as it was already on the way out. Before that I recall trying use wordperfect files in office all the time. So Office compatibility is one issue on the business side, and on the other you have the gaming issues on the entertainment side. However players like Steam may have an impact in this regard depending on how their plans go.
People in business buy Windows because of largely office and other windows only business related software (on the desktop, not servers). People that buy for gaming get windows because most games are only compatible with windows. Everyone else (who you are talking about) pretty much buy windows because it is really the only thing available (other than iOS if you have the $$$). It used to be that common users might be more comfortable with windows, however MS pretty much killed that advantage with windows 8.
On top of all this, what baffles me, is that Windows as an integrated media player is truly horrible with Windows Media Player. I have no idea why this is the case, a company like MS *should* be able to make a decent video player, but they do not. Software like VLC are becoming much better alternatives, than trying to break your system installing malware loaded "codec packs" in an attempt to fix their broken media player. I can only surmise that MS makes it intentionally broken in an attempt to only support official codecs that they can load DRM for the media companies... however is that business worth flushing their brand down the toilet?
Anyway linux while not there yet, and not a lock for surpassing MS, has some opportunities to do so. However likely it would take a large company (like Google say partnering with Steam) to really put a nail in the coffin. Pushing things like Google Docs and the like for office compatibility and transition (particularly when MS starts pushing their Office 365 BS), also strengthening the media software as more and more people use their devices as a connection to their TV, while getting Steam to offer an easy conduit for linux games and developers to market them to a growing user base. Once you have people that are used to it at the office, as a media device, as a gaming device, the common light users will start having more options, and have more people used to the UI. Also if using similar devices say on tablets and phones, this will also raise your common users comfort level, particularly as the demographic that grew up with smart phones start maturing...
So while I don't see it happening anytime soon, it is defiantly something that is possible over time should all the ducks line up in a row.