Adding more than 500 Watts may not be needed but it sure is fun to have.

In reality even 1500 Watts isn't a huge amount of power. I was a touch underwhelmed with my bike when I first rode it, think youtube videos raised my expectations a bit too much.

There are some significant advantages to having more power. Nice being able to accelerate with traffic coming off a light. Also feel there is an advantage having an overbuilt motor not running at max output all of the time. Throw in a cargo bike, trailer, up hill, head winds, mud or snow and the bigger motor quickly becomes needed. Maybe not power so much as torque.

With that said sustaining more than 500 watts really drains the battery significantly cutting range. I do seem to spend the majority of my riding time well under 500 watts, maybe even 250 watts.