This is essential in many situations. For example making broad adjustments to improvised playing, quickly trying out how a line sounds in several different speeds, or even creating complex risers.
Think it like this. You have a phrase in quarter notes that you would like to try in triplets. Currently you either edit all the notes separately, or cut out the section in the arrange screen and stretch there. If you needed to fit two separately improvised lines together you would have to do it note by note. When creating a riser you’d be limited to using the scissor tool to break up the notes or edit it note by note if doing anything more than a single repeating note.
I would love to just select a bunch of notes in the key editor and stretch them as a block! I would also like it to follow snap settings when snap is enabled.
A nice bonus would be if the notes were visible while stretching so that one could see exactly where they end up when releasing the mouse button.