True on the Win 10 point but they had to make a change, they do similar with new platforms all the time, WPF was pushed on Vista.
Basically UWP matches up nicely with other platforms under Xamarin especially. Though most of Xamarin is iOS/Android focused probably because of the market, it closely mirrors those so that it is easier to make a UWP app from one of those apps. Many business apps are going Android, Surface or even iPad/iPhone Apple focused.
Microsoft had to make a hard change for this, UWP is actually a joy to work with on new projects but porting a WPF app may be difficult and you may have to make many custom controls outside touch friendly interfaces.
> WPF & Silverlight runs on multiple Windows versions and Silverlight was supported on Mac OS
True but not for long, Silverlight also no longer runs on any browser but IE.
UWP will evolve, WPF and Silverlight were very rudimentary on their first iterations. Silverlight was solely js based on Silverlight 1 even. Winforms was more supported at the time when WPF came out as well, WPF was only for Vista when it launched, XP it runs slow.
Before .NET and Winforms it was Visual C++/VB apps, MFC, COM+ etc.
Every once in a while things change enough that the old must be thrown out. WPF was a pre-mobile toolkit and Silverlight was for the age of Flash, those times are in the past.
Or maybe it will be replaced with something completely new next year.
This statement is in total contradiction with what UWP is: a platform so OS-locked it doesn’t even run on Windows < 10. On the other and both WPF & Silverlight runs on multiple Windows versions and Silverlight was supported on Mac OS.