1. Web apps are a plus for a secondary device, because you won't need to copy files back and forth, or install sync/VCS software (a hassle for non-expert users). HTML5/Gears storage remove some of the disadvantages by letting you continue work offline. (On the other hand, services like Dropbox have made it just about easy enough for non-expert users to do this with traditional "local" files.)
2. No user-installed native code means certain security concerns could be greatly reduced. All installed code is signed, verified on boot, mounted on a read-only partition, and can be restored to a pristine state by the firmware. Web apps are subject to browser same-origin policies and to Chrome's process isolation. Downloaded native code can run only in the NaCl sandbox. A broken app can't trash all your stuff, because data from each web site is accessible only to that site. (On the other hand, web apps are almost universally vulnerable to XSS and XSRF and to server-side exploits. NaCL has been broken before and will be broken again. The web security model is a start, but it has flaws both in design and in practice.)
3. The interface is simplified in a few key ways. Instead of windows that represent documents within apps and often have their own separate tabs or pages, everything the user interacts with is a tab within a browser. Not a big deal for savvy computer users, but for novices this is one less concept to learn. Everything is a web page; they don't need to be "installed"; they all appear in the tab strip and have addresses that can be bookmarked and emailed. (On the other hand, web apps share only the most basic UI conventions; they are often radically inconsistent from one to the next.)
4. The Chrome team's obsession with speed may prove to be one of those subtle, hard-to-explain benefits. (Like trying to explain why Apple's obsession with detail matters, to someone who hasn't used their products.) I never had a problem with Firefox until I used Chrome for a few days; now any other browser seems painfully unresponsive. Same thing with git compared to darcs/bzr/svn. When more operations move from "fast" to "instantaneous" it changes the feel of the product, and that affects usage patterns.
5. Compared to Windows, Mac OS X, or normal GNU/Linux distros, Chrome OS has less overall code, is conceptually simpler, and has few legacy/compatibility constraints. If it's managed right, this could mean that it will be faster to evolve and optimize, easier to secure, and ideal for experimenting with new technologies and user interfaces. It will also help motivate next-generation web applications and web standards.
But eventually there will be Web apps as good as the local programs for doing what you want: BitBucket, for example, could launch an online editor that integrates with them.
Think how much people use the internet, email and chat. I use my netbook almost exclusively for those things - and I dont think I am alone.
Limits to some of us are freedom to others. It all depends on perspective.
I really do think you are missing the point mainly due to being a power user / hacker. A lot of my friends who are casual computer users a) have netbooks and b) are a perfect target market for this.
Some are already asking me about Chrome OS with interest.
Try to think of it as if your a joe user with little technical knowledge.
Think about people in countries where it's not common to have an iPod that you want to sync 50GB of music to. Or very casual users.
I travel a lot, and I do a lot of programming when I travel. So, I bought an Acer Aspire A150, I got a spare 9 cell battery and I increased the RAM to 2 GB. And, it runs Windows 7 Ultimate like a charm. I have enough battery life to last me a 14 hours of coding movie watching and non-stop music listening. The whole thing is the size of a hard-cover book.
I use Rhapsody for music, which keeps my music libraries synced and Bitbucket for my code. I use Windows mesh to keep other files synced to the "cloud". I can switch seamlessly from my 3 monitor dev box at home to my netbook by doing an "hg pull, hg update"
How does using a "cloud centric" OS help me? Is it cheaper? I got Win 7 Ultimate for free through Bizspark and I have $350 invested in hardware. I don't really see the advantage of hamstringing my OS. Hardware is cheap.
I understand the theoretical advantage to the third world of using less hardware, but when I was in Mexico this spring, netbooks were everywhere. They weren't running Ubuntu, either, they were running pirated copies of Windows.
I'm not trying to troll, but aside from trying to compete with MSFT, how is a cloud centric OS any better than a typical OS?