I do not understand how GNOME feels different since you can setup KDE to behave like you want,
You prefer Andoid/iOS like interfaces on your desktop ? I did not check all apps in KDE but Konsole and Dolphin let you hide the menus(if you need those pixels) also KDE apps let you hide or customize your toolbar so if you nver use the back/forward buttons you can hide them
let me give an example how options are better for me, my right eye is much worse then my left eye so I have the taskbar and notifications on the left, if it was reverse I would move them to the right.
New Qt features are mostly implemented in QML with the high performance parts in C++.
Widgets are mainly for desktop deployments, with QML being pushed for embedded devices and mobile.
That said, I've come to love the layout of Gnome 3 (with many extensions, by default it's nearly unusable). However, its performance is awful. While it's better than it used to be, it's still a leaky mess. I for one hope KDE continues to exist and be supported for no reason other than having a viable alternative when I finally become tired of performance.
As a developer who looked into the two a few years back, I chose QT as it was much easier to work with than GTK. This was before QML, however, so I don't know if it still holds true.