Thank you for the feedback! You may also be interested in this post Outliner GSoC Follow-up Feedback - #80 by APEC by @APEC. I’ll address your questions then share what is currently planned for the Outliner.
This was changed in 2.91. The active object is used to determine what type of actions to allow in the context menu. For example, if you right click a modifier but have objects, collections, modifiers, and materials selected, the Delete option will delete only the modifiers. So we set the active object as the right-click target object to make this work.
What use is the Select menu option?
It is useless, it just needs to be removed. The same for Deselect.
And even though a right-click changes the active object, the Select/Select hierarchy/Delete options in the menu will act on all objects in the selection and not on which you right-clicked to open the context menu.
When I tested the hierarchy was only selected for the object under the cursor during the right click.
I am currently making a design task for the Outliner context menu. There is a lot that should be changed. For example, operators like Delete in the outliner aren’t using the same code as delete in the 3D view. With a few more changes we can easily run those operators from the outliner which will remove duplicated code and make it easier to add more options to the outliner (like duplicate)
I’ll share more once I finish the task.