I found myself nodding with agreement to most of these points as well. Linux developers will do much, much better in all markets if they address these complaints. However, some of the the points are false or exaggerated for effect.
2.1 No good stable standardized API for developing GUI applications (like Win32 API). Both GTK and Qt are very unstable and often break backwards compatibility.
Completely untrue.GTK and Qt are two rare libraries with strict backwards-compatibility rules. It's most of the other libraries on the Linux desktop which break backwards compatibility. The latest versions of GTK+2 and Qt4 will run applications written against GTK+2.0 and Qt4.0 perfectly.
I also wouldn't call the Win32 API "good". Standardized, yes. Good, no. Anyone who's ever tried to write raw Win32 GUI apps knows what I'm talking about. And if you don't use Win32 directly, then you don't have a standard. Which would you prefer? MFC? ATL? Windows.Forms? Avalon?
5.2 No games. Full stop. Cedega and Wine offer very incomplete support.
Completely untrue. Yes, fewer commercial games appear for Linux, but fewer commercial games appear for the Mac, too, and no one says the Mac is not ready for the desktop. For commercial games, there's all of the Unreal Tournament games, all of the Quake games, all of the Doom games, all of the Descent games, as well as community ports of Duke Nukem 3D, the Serious Sam games, and countless others.
Aside from the commercial titles, the games that ship with either KDE or Gnome are as good or better than the games that ship with Windows, and 90% of the PC population only plays those games. (KNetWalk is a great game that would sap millions of hours of productivity from the world if it shipped with Windows.)
You can have a ridiculous amount of fun on Linux with console emulators. There are great clones of other games too, such as FreeCiv and LinCity.
Finally, it's not fair to discount the games that you can play with Wine. I purchased and played Half-Life 2 from start to finish on Linux, and it worked perfectly. I didn't miss Windows one bit.
12. Bad security model: there's zero protection against keyboard keyloggers and against running malicious software (Linux is viruses free only due to its extremely low popularity). sudo is very easy to circumvent (social engineering). sudo still requires CLI (see clause 4.).
And what security model would the complainer prefer? Yes, sudo can be circumvented by social engineering, and Mac OS X basically uses sudo to do admin tasks. On Windows, you don't need to do any social engineering to circumvent the "run-as-admin-by-default" policy.
Redhat-based distros have lots of protection against keyloggers, viruses, and break-ins because SELinux is turned on by default.