Just a side note regarding the horizontal bar. This one is really useless if you have multiple notes with different lengths and you want to make them have the same velocity. Since the horiontal bar of course is relative to each note you can't really compare the horizontal bars of both notes and have to look at the velocity lanes at the bottom... so we really need a more sophisticated way of visualising note velocities.
Here's a typical piano recording that shows what I mean (screenshots are still V2 because my notes for this FR are from 2013):
Here's how MIDI editing of a similar part looks in my old Cubase 4:
For me that's quite handy... I immediately see which of the notes have the same velocity and which one I have to change to make the chord sound well-balanced.
Now you may ask how this plays together with multi part editing where every track / event has its own color. I think in this case Cubase has implemented it in a great way: You have a dropdown list in the editor where I can select how you want notes to be coloured (Velocity, Pitch, Channel, Part, PPQ grid, voice, chord track) ... sorry for the German captions ;-)
The standard coloring is blue for lowest velocity and red for the highest:
In my opinion that's nearly the perfect solution. In the settings you can adjust the color for lowest and for highest velocity. A nice enhancement for a S1 implementation would be to also have controls for setting opacities or color intensities. This way we could have both multi part editing with part colors and differently looking notes depending on the velocity (darker / brighter)..... or just two colors like in the Cubase screenshots :-)