CP can live only in main toolbar. It is usual to turn off toolbar on a screen with small resolution and get bigger area for editor and other windows. But form editor users can't use this arrangement. Main toolbar is also far from form editor. CP is hard to use with many components in one component category.
User have to scroll components one by one to look for some component.
It is also problem to distinguish between components only by icons. Tabbed pane CP is not suitable for more component categories. More then one category tab rows make toolbar too wide. Tiny version of CP partially solves these limitation. It allows to shrink toolbar to one line.