On most systems, and especially those without a tonne of power, we need a low buffer for tracking and a high buffer for mixing. We switch between the two for a difference in CPU/Disk load that the Constrain Delay Compensation just doesn’t handle.
With a buffer switch button we could set our tracking buffer and mixing buffer in the device setup, and then easily switch between the two, without having to go Devices > Device Setup > VST Audio System > Control Panel, every time we want to change our buffer size.
At very least a shortcut to quickly adjust buffer size.
Or even simpler a shortcut to Device Setup. It is incredibly rare that I open Cubase without going to device setup at some point in the session.