One could argue that GNOME gets it right because the most popular Linux distributions use it by default. That might hold water if Linux desktop market share was growing rapidly thanks to these distributions. The pitiful desktop market share of Linux would argue otherwise. These distributions are popular, but they're popular among those who are already familiar with Linux, the segment to which GNOME is more likely to appeal. GNOME is attractive to some seasoned Linux users because it one of the few complete desktop environments that is more lightweight than KDE, which makes GNOME more appropriate for use on servers. The limitations in GNOME are also unobtrusive to someone who knows how to get around them; someone who is unafraid of the GNOME registry or the command-line.
What must be done to remove this obstacle? Red Hat endorsed GNOME due to licensing issues which arguably were resolved long ago. SUSE favors GNOME because one of the early GNOME developers practically runs the company. Heaven only knows why Ubuntu defaults to GNOME (though you can download and install Kubuntu, which defaults to KDE). But if these distributions want to contribute to the expansion of Linux on the desktop, they need to adopt and promote KDE as the default desktop and/or pressure the GNOME developers to abandon their brain-dead development philosophy. This is especially true of Ubuntu, which leads the way in getting Linux pre-installed on popular brands like Dell. Linux desktop market share will probably grow regardless, but it will grow faster with the more popular distributions backing a sane graphical desktop.
Open Document Formats Will Drive Adoption
Linux has a dual-legacy to unseat. Windows and Microsoft Office are practically synonymous, and there is no Microsoft Office or fully compatible suite for Linux. Either users must make the switch to open document formats, or Linux applications must support perfect imports of Microsoft Office files. The ideal solution would be to migrate to open formats, but the market will decide.
This obstacle isn't nearly as insurmountable as it seems. One should recall that WordPerfect once virtually owned the word processing market, yet people still found a way to migrate to Microsoft Office. Microsoft will make any transition from Microsoft Office a difficult one, but it is still possible. The appeal of open document formats is undeniable. It has to make more sense than the nearly one-way trip people took to Microsoft Office. A move to open document formats is a move toward guaranteed compatibility in the future.
The Bottom Line
Despite the obstacles involved, there is good reason to be optimistic about Linux on the desktop. This author has been using desktop Linux almost exclusively since the mid-90s, although it required a lot more computer savvy back then than it does now.
There is one additional factor that cannot be overstated. To anyone who truly knows what free software means, they know that "free" as in liberty is the greatest strength of Linux. However, one cannot deny the power of "free" as in "free beer." Microsoft applied this power to make Internet Explorer the most popular browser in the world. Netscape faded away because the company was unable to compete against free as in beer. Firefox has only been able to fight back because it, too, is free as in beer. Of the three top competitors on the desktop, Windows, Mac OS-X, and Linux, only one of them is free as in beer. That will go along way toward making it the de-facto standard on the desktop.