Yes it's far better to buy the battery, but that makes the car very expensive initially, and as you say, if it fails early, you are responsible for replacing it. The biggest downside for most people is the range, my average trip is about 120 miles, so I couldn't even do one trip on a full charge, and at highway speeds, a full charge can last just one hour. I'd get really cheesed off if my phone needed charging one every hour! I think they are great for short city trips though, helps keep pollution levels low. I'm not sure if it's the same there, but in the UK there are already lots of free charge points.
I know what people say. They want to keep their options open and spontaniously drive from glasgow to london pulling a horse trailer through a field if they feel like it.
Im just saying it really works for daily driving and more 25000miles/year in our case. A planned quick charge along the way having a bite to eat or a coffe, go shopping for grocerys etc instead of arriving tired is just fine. For a daily commute, you could not afford the gas to have a longer one anyway. Longer trips are really better by train.