I spend a huge amount of time locking and unlocking when I want to edit one item deep in the board design. The big problem with capturing lots of elements by dragging with the mouse is that you capture all the sticky notes and other interactive elements which should stay un-locked. So I first need to move them out the way, unlock, edit, re-capture all the elements I want locked, then lock them again. It would be so easy if I could unlock, edit, re-lock the same elements.
Other locking nice-to-haves would be
“lock everything except stickies”
“lock everything but allow text editing inside locked blocks”