Hi
A tab with a drop down menu would mean two key presses to access your clips each time. 
Note also the the Sequence bin differs from the others in that the contents are transferred to it from the Timeline and are not imported from external files like images, audio and video clips (although some VP functions do create copies to these bins). The latter are used to create your timeline where you can edit them and arrange them etc. but then, once you have created a section in this way you may feel the need to save it-or "put it to one side" so to speak.
To allow this, the whole edited section can be transferred to the Sequence bin by clicking the + sign that follows "Sequence 1 X" on the left. This clears the timeline for editing further images and clips.
The edited sections now in the Sequence bin will behave as complete clips as they have-so to speak- been exported, and can be stored there one at a time as editing is done. At any time they can be added to the ongoing timeline as normal clips or to an empty timeline in order to assemble the finished article. It's logical when you think about it.
Nat