The way Mark described it to me was like having an elastic band for the throttle cable while in 1-3, so when you put you foot down you do get 100% of the power you're requesting, just not immediately.
If that's correct I guess it's a design decision on Nissan's part to make the car nicer/smoother to drive around town etc - it is a GT after all. Living in London I found it a bit less comfortable around town after getting an Uprev, however you quickly get used to it and I'd rather have the control myself rather than leaving it to the car to be smooth.