I have voted for this feature, because it would be great if we had more shrink/grow options.
A cool feature would be, if we could toggle the shrink state of multi-out instruments.
Or if we could shrink/grow all busses or otherwise grouped channels.
But note: You can already shrink/grow individual channels:
1) Hit the shrink button <> to shrink all channels (= activate shrink mode).
2) Doubel click on those channels you want to shrink or grow. You can select multiple channels.