[Works]

I did post this question to few other forums as well and got this interesting reply elsewhere:

"My car does the same thing. I believe this is designed behavior by BMW to smooth out throttle inputs and make the car feel more "luxurious."

I know on E46s, the same feature was called anti-jerk, and could be disabled through tuning. I haven't been able to find any tables to do so within MSD8X, but there's a chance they exist somewhere.

As you observed, the throttle smoothing only activates while the car is moving and the ECU sees the clutch pedal up. I wired in a switch that interrupts the clutch switch wire to the ECU to get around this. When I interrupt the signal, the ECU defaults to seeing the clutch pedal as down, and does not activate the throttle smoothing in any scenario. Downside is, you lose gear detection, and therefore boost by gear won't work. Also, cruise control won't work, but since I have a switch, I can just flip it back on if I need either of those. Beyond that, I have noticed no negative effects. The car just feels much more responsive, and in my opinion, a lot more fun to drive."

Sounds like I'll have a weekend wiring project ahead of me for the next step to try out.