I concur about Windows Vista. For all the criticism that OS received, it did bring Windows a compositing desktop similar to Mac OS X, which was a crucial milestone to the GUI experience, which brought compositing desktops to more than 90% of personal computer users.
I believe Windows 98 and ME were omitted because this is largely a presentation of the evolution of GUIs. Windows 98 and ME did not substantially differ from Windows 95 in terms of their look-and-feel; the same can be said about Windows NT 4 and Windows 2000.
> Windows 98 and ME did not substantially differ from Windows 95 in terms of their look-and-feel; the same can be said about Windows NT 4 and Windows 2000.
The only differences I remember are quick start icons in the taskbar, and gradients in window title bars.
I believe Windows 98 and ME were omitted because this is largely a presentation of the evolution of GUIs. Windows 98 and ME did not substantially differ from Windows 95 in terms of their look-and-feel; the same can be said about Windows NT 4 and Windows 2000.