What happened to the Year of the Linux Desktop?
There are many reasons Linux has not matured as early adopters foresaw or hoped. If I selected only one specific point in recent time I would look at how development shifted with desktop environments.
The KDE folks dropped KDE 3 and started KDE 4. Nobody seems really interested or cares other than KDE developers.
The GNOME folks dropped GNOME 2 and started GNOME 3. Nobody seems really interested or cares other than GNOME developers.
The Ubuntu folks dropped GNOME 2 and started Unity. Nobody seems really interested or cares other than Unity developers.
From an enterprise support perspective, KDE is the preferred desktop environment for the Suse folks, nee, Novell. GNOME is the preferred desktop for the Red Hat folks. Unity for the Canonical folks.
A common denominator in this shift in desktop design?
The idea of convergence is to create a common foundation for multiple interfaces. Sadly, a true free/libre tablet or phone has yet to appear. Possibly might never appear because of the challenge vendors will have preventing the software from data mining, which free/libre users do not tolerate.
That means these converged desktops are being used by traditional desktop and laptop users.
The “swipe” tablet and phone interfaces do not work well on traditional desktops and laptops.
Hopefully one day all of this works out.