Aaron Seigo, a KDE and Plasma developer, writes about free software, desktop design, multi-process architectures, and Plasma Active devices.
HN links it for KDE history, such as the slow adoption of QML in Plasma and the blunt 4.0 release notes.
They started migrating several releases before 4.10, maybe that's why.
To sum it up, I'll paste this: "In short, QML makes it very easy to write fluid user interfaces, while retaining speed. The advantages expand well beyond the mobile application sphere, and represent a new way to do GUIs." http://jontheechidna.wordpress.com/2012/05/19/my-thoughts-on-qml-and-the-desktop/
QML is part of QtQuick: http://en.wikipedia.org/wiki/QML
Aaron Seigo also had some good points on his blog (If I remember well) but I couldn't find them now. Check his blog nevertheless, it's worth it: http://aseigo.blogspot.com/
Not really. Take a look at this blog post written right before the 4.0 release by kdesktop's maintainer who founded Plasma:
http://aseigo.blogspot.com/2008/01/talking-bluntly.html
To quote:
KDE 4.0.0 is our "will eat your children" release of KDE4, not the next release of KDE 3.5. The fact that many already use it daily for their desktop (including myself) shows that it really won't eat your children, but it is part of that early stage in the release system of KDE4. It's the "0.0" release. The amount of new software in KDE4 is remarkable and we're going the open route with that.
It is not just technology, see the addition by Aaron Seigo at http://aseigo.blogspot.com/2014/03/more-on-why-display-server-does-matter.html. I also wrote a blogpost about it: http://blogs.gnome.org/ovitters/2014/03/25/on-change-management-and-display-servers/, but then more stressing on ideas from change management theory vs the approach Canonical seems to be taking.
Competition with what? Windows, OS X? Xorg?
Edit: Can't seem to reply to child, but Mir isn't really a credible competitor (See: http://aseigo.blogspot.com/2014/03/more-on-why-display-server-does-matter.html . Unfortunately Mir seems to be mostly NIH; everyone else is cooperating on Wayland.)
An interesting post on this subject by Aaron Seigo:
http://aseigo.blogspot.com/2014/07/one-singular-sensation-your-email.html
How would people compare this to Improv? http://makeplaylive.com http://aseigo.blogspot.co.uk/2013/11/introducing-improv.html