It is much more simple to have 1 icon to get access to the control center, instead of 2. On some installs of TDE, the 2 control centers are installed, but you don't even know which one will start when you click on its icon. On KDE 4, you can switch between the 2 presentations modes as much as you like it, and you don't have to check out which icon is the right one. I can say on this that I prefer the old-fashioned Control Center.
-Alexandre
I agree with Alexandre on this one. Hope r14 is coming soon