I think there’s some misunderstanding here. It’s about the simultaneous use of different articulations. Concerning the number of articulations, I immediately wrote that it was beside the point, since legibility is the same. But when @SteveInChicago wrote about “20 articulations at a time”, I realized that some people would be using Expression Maps for sheet music (which, granted, is what Steinberg set out to do here). In this case Expression Maps are not mutually exclusive (you can have several of those superposed), and the current implementation makes sense.
However, I presume many other people, like myself, never use the Score Editor and are using Expression Maps solely to send keyswitches in order to select from a vast array of discreet articulations in a customized sample player (think VSL matrices or a custom Kontakt multi). In that case the articulations are mutually exclusive and there is no sense to them being superposed.
Cubase is smart enough to allow the user to draw an articulation above or below another one when possible, or cut the current one off and insert a new when it isn’t possible. It all depends on the Expression Map definition. IMHO it would be helpful to at least have the option to display only superposable articulations as row, and keep everything in one row in the opposite case.
@jono not bono, I understand it’s no big deal to you, but I spend more than half my time in Cubase in front of the Key Editor…