I never thought about it too much before, but I can see some usefulness for that "feature". If you're editing a midi performance and decide that the high velocity notes are a little too aggressive, you can select all of the notes above a certain velocity and bring them all down together.
You can pan the piano roll so that all of the notes are out of the frame and only the velocity lines are showing. Then lasso the tops of the offending velocities. Pan back down to see the notes and, using one of the selected notes, pull the velocities down to where you want them.
Could be useful, no?
Doug
Say, Beep, how do you hide the velocity lines?