You have to consider the functionality as it pertains to the job it is meant to do. The MacBook Air is meant as an extension of the person's existing computer, a midstep between an iPod Touch and a full-sized laptop. It comes with a power adapter and display adapter, yes, and you can get the Ethernet adapter and SuperDrive, but really, this isn't meant to be a full-bore laptop.
This is meant as a machine for you to carry around with you when you wouldn't be carrying a full laptop, but you don't want a compromised experience for basic functionality like word-processing, spreadsheet, database, the internet, that sort of thing.
No, the optical drive isn't supposed to come with you, because really, what are the primary uses of an optical drive? File transfer, software installation, and accessing media. File transfer is better suited with a USB thumbdrive, or, better yet, 802.11g/n. Media, in general, relies less and less on physical storage. Finally, when was the last time you decided to install software while away from your workstation.
As for the non-removable battery... Do you use a second battery with your laptop? I don't, and I don't know anyone who does. When I'm at home, I plug my laptop in and charge it. If I'm not going to be home for more than five hours, I have a tendency to bring the AC adapter for my laptop with me anyway because it's quite light, and I can simply toss it in my backpack with my other stuff. It sure is a heck of a lot cheaper to carry it with me than buy another battery, and a charger for it.
It's larger than a normal ultraportable because it's not expected to be used exactly as most ultraportables are used, as miniature laptops. It's meant to be put in with your other stuff, and used when you normally wouldn't even have a laptop with you. It is the size it is because they reduced weight and thickness, but kept it large enough in dimension that they could put in a full-sized keyboard, and a screen easily viewable by the whole population.
No, it doesn't have all of the features that other laptops have. It's a Porsche Boxter to the other laptops Mercedes SLK. Both are small and light and about the same price, but the Boxter isn't compromising it's tossability and driving experience by trying to be both a roadster and a coupe.