I completely accept your rationale for not having addressed this in the past, however given the increasing use of laptop + controller (be it keyboard, pad or grid types) , having these hooks and providing a development framework (preferably Python - due to its popularity and no more) to allow template development i would see as a key priority for growth in new users.
 
Here is a tongue in cheek view...
 
Without dedicated templates for the APC and Launchpad, Ableton Live is nothing more than matrix view with a below average DAW attached.
 
 

Noel Borthwick [Cakewalk]
The root problem is not replacing CAL. It is exposing the object/document model to the outside world. 
Designing and exposing an interface to all the internal objects is the main job here. Choosing a scripting language to access that is secondary. Obviously CAL itself is obsolete and inappropriate.
I've wanted to do this since I joined Cakewalk but its a big project and its been difficult to justify spending resources on since we have a big pipeline of things to do.

SuperG
You're barking up the .NET tree. This is something that would be language agnostic.
 
I've done an application scripting interface based on the Sony Vegas model myself.
 
But the issue is, as Noel pointed out earlier in this thread, this problem is having a congruent 'doc/object' model.  Get those particular ducks in a row first, then adding a scripting interface is straightforward.

 
.Net is what I know best, so I use it for examples.  I agree with you 100%.