Drag and drop is one thing we just don't really use more than, say, once every 1/2 hour.
There's no composability really. We have the stupid metaphor of an "App" and it's a little world in itself. You can't really plug things into each other - e.g. use the gimp brush tool in a facebook post.
It's a dead end.
Why ** ** do we have to have a modal dialog to save a file when there's a perfectly good file manager?
I used to use the ROX window manager and ROX Desktop - they were a great export of RiscOS features to Linux. I liked the way I could customise a menu option with a hotkey so easily. It's no longer maintained and I wasn't smart enough to be able to do it myself then. Perhaps now... :/