You visit the key editor hundreds of times, but there is no way to quickly bring all the notes in your part/selection, so they fill the whole of the main window. Zoom to Locators only manages the horizontal view.
So, perhaps a little red button, that is located in between the horizontal scroller, and the zoom scroller (RHS of Key editor window) that either (depending on whether notes are selected)
a] Brings all of the notes in the part to fill the whole of the window
b] Brings only those notes selected into the whole of the window
Using such a button you could say, select four or five notes - click the button to get macro view of these notes (easy to edit then) then when you are finished, deselect the notes (by clicking anywhere) then hit the magic button again and you straight back to viewing the whole part.
Fair point about keyboards, its usually out of reach when I work in the studio, too many other instruments, controllers, keyboards, gtrs - I go with a mouse where I can.