This is a common misconception. In fact, e-bike users end up spending much more time on their bikes than users of non-electric bikes. You can still pedal as much and as hard as you want, but you can also be rewarded with a pleasant boost when you feel like it. This makes biking even more fun. It also removes one of the obstacles to people using their bikes to commute to work, and makes e-biking a great way to get back into training and improve fitness.
Everybody who has ridden a bike to work is familiar with that feeling on a Friday night after a long week and the wind is blowing: "i'll just take a cab or bus, i'm too tired" With an electric bike those arguments will disappear. Without a thought you will jump on and ride home, enjoying the freedom and liberation it gives you.
For many people, getting back in the saddle after a long hiatus is hard work. It takes a long time until your fitness is built up to the point where the ride is actually enjoyable. For most people, particularly those with busy lives, it is too much of a hurdle to overcome. Electric bikes allow you to enjoy the ride from day one. Allowing you time to gradually build your fitness and rely on the motor less. Its lower intensity but more frequent.