I also encounter this very often when I have a complicated components or components with vast contents. I attached a video showing same problem and I hope that this will attract more attention from the community for others to share what they encounter as well. So that Adobe will respond to this glitch or problem.

The recording is the same date as this post.

I agree too! There are popular scenarios that require to expand the bounds of a component without scaling. Actually I'd expect adding a new element to outside of an existing component's bounds automatically expands the bounds just like groups (or symbols).

I agree. When increasing the size of some parts of the component's content or moving an element to an area which is outside the component's bounds, the component clips/masks everything outside its original bounds. When trying to increase the bounds, it actually resizes everything in the component (depending on the responsive resize settings).

Similarly, if moving elements inside a component closer together, the component bounds stay where they were initially and then are larger than necessary for the contents.

Existing workaround:
Move/resize the elements how you wish. (There will be clipping or superfluous bounding space of the component.)
Select all elements inside the master of the original component.
Create a second component with them.
Go to the components panel and delete the original component.
Now in all previous instances of the deleted component you still have the elements inside the new component, which is again fitting exactly to the contained elements.

Suggested improvement:
Drag a component's resize points while holding CTRL or ALT (or something else) to only move the bounding box without resizing the component's content.