yeah, this is driven by ‘piano mentality’ … a note can only be pressed once.
unfortunately, this is pretty much widespread, even in daws and vsts supporting MPE.
I used to comment on it, but gave up, felt like battle Id never win…
(esp, in daws using piano rolls… where they will struggle to represent two of the same note being played)
perhaps one day when MPE is in widespread use, and developers are more in ‘refinement’ phase then its worth revisiting… but at the moment, I suspect we should be happy for what we get 
in fairness, I slightly ‘tripped over it’.
I knew in Live 10 they’d added a lot of features for automation editing, and wondered what they’d included in the expression editor…
I found the offset quite quickly but the scaling, I did by accident and couldn’t reliability reproduce it…
offset is done by getting close to the automation line (but not close enought to add a point) , then dragging.
scaling is similar, ensure all points are selected, but then be just outside the region of the note expression (to the right) the start dragging.
Ive a suspicion this might still be a bit ‘work in progress’ , since its takes a bit of ‘practice’ to do this, its not very intuitive, as there is not alot of visual indication that you are in the right position.
edit: created a suggestion (L11-SUG-0662) to improve the UI to make it a little more intuitive