This function opens a contextual menu which can be a little messy when the class hierarchy is huge (> 100 derived classes).
First, the mouse wheel doesn't work to scroll in the list. We need to press the top/bottom arrows on the list to navigate which is super slow.
In case where we have several levels of inheritance (child classes, grandchild classes, etc...) I think the most useful information is not easily visible: what are the direct children of the class.
Consider a class hierarchy like this:
Starting from Base class, I want to see all direct children (A, B, C) but the Derived class contextual menu is full of A1..A1000 entries.
As for the feature request: can you add a new entry "Direct Derived Classes" in the Goto Related menu, which list only the direct classes of a given class?