Electric bicycles are good for city use, but really only city use. They let you breathe less fumes, don’t emit much pollution, let you commute to work without being sweaty, and carry your groceries home up and down the hills without much effort. They make daily life a little more convenient without the wastefulness of a car.
If you’re cycling for any other purpose, however, I would recommend against going for an electric bicycle as your only bicycle. Electric bicycles are particularly terrible for long-distance riding, since with current battery technology they tend to only run for 15-40 km on a single charge, and take hours to recharge (unlike gasoline motorcycles which are recharged with a simple fill-up). While electric bicycles can usually be pedalled when the battery dies, the bicycle is heavy and difficult to pedal uphill manually and quickly becomes impractical as a vehicle when it loses charge. I would hate to be stuck in the middle of nowhere with an uncharged electric bicycle.
On the other hand, a nice, light road bicycle is always a practical vehicle (as long as you carry some basic tools to fix flat tyres) and you never have to worry about losing charge as long as you have food and water available; non-electric road bicycles can easily be ridden for 80 km on human power in a day by an average adult, upwards of 150 km if you’re an athlete, beating out an electric bicycle’s daily utility by a large margin.
Another big disadvantage of electric bicycles is that laws vary regarding their use; they aren’t always allowed in every country, city or state and may have different licence requirements depending on where you are. For example, they are banned in Shenzhen, China but allowed in Beijing, China. Every state in the United States also has differing laws about registration, licence requirements, age requirements and restrictions on motor capability; even DC and Maryland have very different laws. Human-powered bicycles, on the other hand, are allowed hassle-free almost universally everywhere in the world, and gasoline motorcycles generally have more consistent laws across the provinces of any given country making them suitable for long-distance domestic travel.
I do hope though that electric bicycle and battery technology improves and that laws become more consistent over time. At the moment, they still bear the disadvantages of being an early-stage technology.