KICK 2 is amazing!
But there really is something that would take it to the next level for a future version, and that is:
The ability to automate points on the various envelopes. I don't mean automate all points, that would be overkill.
But the ability to define a couple of points that can be automated on their X and Y access. Then the plugin would make only this (or these) points automatible by Cubase or Ableton or whatever.
Because when, for example, you're making a snare roll (yes, K2 is just as amazing for making snares) you might want to change the envelope slightly as the velocity (for example) increases.
You can already achieve quite a lot of the already automatible controls, especially the lenghth slider, but this would take it to the next level.
Here's an idea: how about a KICKstarter campaign to fund the coding work required?
On a somewhat related note, some modulation functions inside the plugin would also be amazing, like map velocity to the "length" slider. And then the ability to draw a transform curve so that one could exactly tailor how the velocity modulates the destination.