I can't understand, why you made system settings so... weird
I think half of settings can be stored in "Look and appearance"
And please, let me choose, what I want, blue panel, black, or maybe red, and transparency, separate from desktop effects, because I want (for example)opaque panel, with desktop effects on! or half transparent blue panel in elegance style.
And I think, not only me
If you want it to be simple for new users, you can make it in three stages:
One click - to choose complete theme with icons, colours, window style and maybe even sounds.
Standart - choose diferent themes for panel, windows, background, menu (as it is now in desktop details)
advanced - custom configuration of ewerything, don't care about themes, total control, blue panel, red window, cde style, wobbly windows
I'm not first who is not happy with theme configuring in kde4. And I hope you working on it hardly
good luck

There is no doubt that system settings needs some work. There are three primary problems:

1) UI design of the modules
2) Organization of the modules into meta groups
3) Navigation controls to browse and search through the meta groups

I wish I could say that we are working on it, but unfortunately there aren't enough hours in the day I think in the meantime, someone is adding a treeview functionality (similar to KControl) to help navigate the poor information architecture until a better solution is designed and implemented.

I am one of the developers working on KControl. It was designed with a completely Plugin architectured view, along with many convienence classes providing a easy way to show the information to the user and load modules. It should be easy to add further modes in the future, once the convienence classes are finished ( loading modules is currently under development )

Kcontrol was better than systemsettings, but it was not perfect, appearence and look settings were in one place, desktop effects (shadows and opacity) in other, and few more annoyances.
The main problem I think is that developers and users think different.
Developers think: - here goes plasma, and here kwin controls, and here we choose kwin or metacity, and so on...
But users think: - here's appearance settings, here must be all controls of how my desktop will look like. Here's keyboard controls, and it is strange that keyboard shortcuts are somewhere, but not here.
If you can't think like users (I understand you), give your kde to group of people that never digged it to deep, ask them to change something on theyr desktop. What they will do?