Another big advantage of modules is that those guys who like more than 61 notes or weighted action (and there are many) could use the master keyboard they prefer and still be playing a Tyros3, Korg PA2X or Roland E80 - IF - these manufacturers produced the modules.
Most would probably have 2 modules on the top - quite a lot to go at there.

Not going to happen! - I know, but it still makes sense and we can dream.
Tony