[ksaj]

I asked Google this very question earlier today, and got a great answer.

With the electric motor, when you "step on it" you get a loud droning sound that does not rise with the speed as a driver would expect. This really messes up their perception of the actual acceleration taking place. The progressive nature feels like you're being launched from an elastic band.

By skipping degrees to emulate gear shifting, you get that scooping sound one expects when accelerating.

As for the "roar" part... that's a different topic that probably plays more into nostalgia. Hopefully that's only through the inside speakers, and not audible outside...