So, I've got a couple ideas for simplification, without loosing ability.
This is what it currently looks like. There are two "Appearance and Behavior" sections. Also, there are too many options you'll never click.
This is my proposal.
Let's put all the personal options: IM, Account Details, and Personal Info into one place.
Let's break out passwords so that it's obvious we can control our passwords.
I'd pull out certain things and combine others in all areas; but I've not proposed any KCM be removed although I can't place Information Sources.
Most of the Network and Connectivity section can be rolled up into a Network item.
This is the current shutdown dialog. Note the options we already have chosen from. These three options are severely redundant and a bit confusing.
The other thing that felt out of place to me was the moon. Are we saying good night? It feels part of an astrological theme I wasn't aware I'd set my computer to.
However, I like the countdown attached to the "Are you sure?" dialog.
Also, It's not clear in the slightest what exactly those down arrows do. It requires you to hold the button down to open the menu. This is very bad design for such a button. If you don't immediately figure out how to get the menu to open, you have to wait for your computer to shutdown and reboot in order to try again.
Notice the simplified OS selection, like GRUB (v2) currently does. Advanced OS options are best left to the user to choose in the bootloader itself.
You may have noticed I've used widgets, this is not for any reason other than the fact that I know how to use Qt Designer and not Plasmate.