both torque and power are important

First, I agree with you that acceleration is directly determined by torque. At low rpm, torque curve is mainly determined by max torque an engine can generate. At high rpm, torque curve is mainly determined by max power an engine can generate. (I know this is a bit too simplified)

It is like a person in a 100m race. When you just start, your speed is low. Your legs generate the largest force to kick the ground. Once you are at high speed, you can never kick the ground that hard. Your acceleration is determined by your max power. How much the largest force your legs can generate does not matter any more. You don't see a body builder with huge muscle in his legs win a race, do you?

For people who always shift before 3000rpm, power does not matter to them. But when you want to accelerate fast, you do want to use the high rpm region where power becomes important. If there are two engines with same max torque, usually the one with higher power either give you higher torque at high rpm, or can rev to higher rpm. (like s2000 engine) Thus you can shift later and accelerate faster.

I think the more interesting question is for the same engine in the same car, how do you tune it to accelerate the fastest.