Not so spontaneous, intended acceleration

[Loren]

It's a "learning" system. You may want to try resetting it to default so that it can learn YOUR driving habits.

The throttle pedal is definitely not linear. Think of it as a "demand" pedal. Where you place your foot and/or how quickly you move it are the inputs that the ECU uses to assess what you want it to do. It then uses that input and many others to determine how much to open the throttle, how to set the valve timing and ignition timing, whether to go rich (open loop) or use the O2 feedback to keep the mixture stoich, etc.

Most people complain about the opposite problem, the DBW system is not sensitive enough. And maybe that's what you're feeling? It's not sensitive to a small input, so you give it a larger one... which it then responds to.

Give it time, it should learn you and you will learn it... you'll get used to it.