Right click on empty space on your panel and click on Add to Panel and there you can find Drawer applet 
. It looks like this when you open and can add stuff in. 
One of the technical reasons is that different packages are responsible for different aspects of the system. Some settings (ie. Keyboard Shortcuts) apply to Marco (a CPU-driven window manager), but some may not necessarily apply for Compiz (a GPU-accelerated window manager).
All options are categorized in one window -- the Control Centre -- but are also found in their categories on the System menu.
I know all that, and the reasons why it it the way it is but still would be nice to have things grouped into one window managers for related settings, so ultimately you'd only have 4 main settings windows for the entire system. I don't mean like control centre, which just has the icons to separate instances. I'm not really complaining but just putting my thoughts out there for future reference for anyone.
Thank you very much for that. Hmmmm, this feature isn’t at all what I was hoping it would be. Ah well…
My drawer applet idea is completely different, because you could assign folders as tabs that stick out from under the side panel or even the edge of the screen. This system one is merely another menu on the panel which leads to folders.