The battery won't just stop working after 300 charges, it'll just retain 80% of its original battery life.
Also, there are many reasons to buy a MBA that don't include the "COOL FACTOR". Sure, asthetics count, but here are why people buy MacBook Air's. They need a full featured notebook, without much compromise on speed, screen or display, but need it to be thin and light as well. The MacBook Air is the only notebook on the market that gives you a 1.8GHz Intel Core 2 Duo, 2GB of DDR3 RAM, an SSD, an LED display, full sized backlit keyboard, multitouch trackpad and weighs only 3 pounds. Netbooks are NOT an option if you want a readable display and a notebook you could really use in the real world. The Macbook Air is perfect for those things.
So please don't tag everyone who owns a MacBook Air as someone trying to be "cool". Take some time and learn about the consumers and the target market for the product. Just because it does not suit YOU because you don't appreciate the thinness or weight (or lack thereof) doesn't mean you shouldn't be able to understand other people's decision to purchase one.