Thoughts related to the Windows 10 "Desktop is a desktop, no "Start" screen" thing:
From 1984 to 1990, there was a serious debate as to which was better, the command line or the WIMP (Window/Icon/Mouse/Pointer) UI. Why? Well, because Mac OS's Systems 1-4 were user friendly in the sense people knew how to use them, but user unfriendly in the sense that they got in the way, were kludgy, awkward to use, and offered zero advantages - beyond a lack of training for users - over the command line. At best you could say some applications needed a mouse, but some, such as word processors, were actually harder to use in the prehistoric era of WIMP user interfaces than the keyboard based versions.
What changed? Microsoft Windows. From Windows 1.0 onwards, Microsoft offered a vision, initially a very, very, ugly vision, as to how a computer could be more, not less useful with a WIMP UI. The critical feature was multitasking. Windows offered a better way to multitask than command line based systems, because each Window, representing an application or document, could co-exist in the same "world", the desktop.
Windows wasn't anything like the best implementation, but it was the only implementation of the concept available on standard PCs.
When Microsoft pretty much forced manufacturers to provide Windows and a mouse with all MS DOS based computers, users had a straight choice of using one UI or the other, and they overwhelmingly chose Windows. By comparison, when GEM was bundled with many PCs in the late nineties, GEM was a nice to have that was ignored by most users (anecdotally, outside of stores, I never saw an Amstrad PC1512 running GEM in the wild, despite it becoming with it and being a major advertised feature.) GEM, a Mac OS UI clone, did not offer multitasking.
1. Mac OS released around 1984. Causes schism between WIMP and command line users
2. Windows 1.0 released 1985ish. Most users recognize it's a very powerful system, but are put off by user interface and memory requirements.
3. DOS vs WIMP rages for next five years largely because Windows is crippled by other factors.
4. Finally PCs are forced to be powerful enough to run Windows in 1990, and Windows UI improved enough to be "good enough" compared to Mac OS. Everyone jumps to Windows. End of DOS vs WIMP debate.
Touch UIs? Where is the touch UI that is more powerful, as opposed to being easier to use, than the WIMP UI? It took Microsoft (and Commodore too) less than a year to come up with something that was actually an improvement on the command line having seen WIMP. It's been nearly a decade now, who has come up with a touch UI that is more versatile than a WIMP desktop?