The only reason to use blender and why blender has one, is CG animation work. It would be silly to have the interface where you do exactly the same thing as in a video editor, except with the timing of animations instead of footage, but not have one for footage as well. Especially if the animation sometimes depends on when which part of the footage plays.

Rendering, exporting, importing, finding a detail is wrong, is more annoying than having it right there in the same UI.