I think the idea is to disconnect pedaling from road conditions.

When you’re biking, it’s preferable to pedal in “safe” zones (protected bike lanes, trails etc.) while relying on the battery for eg intersections and when sharing the road with vehicles. With a regular bike you have to pedal harder precisely at these zones which makes it a little scary. You can also pedal on fairly flat ground/use all that energy to climb up a steep hill quickly without pedaling etc.