It's commercially attractive for techsavvy audiences that wont go through the time and trouble to download and run an indy game with short gameplay. So to make them play your game you just want to give the experience right away. A browser plugin is not made for playing a 80mb game, but rather a browser aimed game. I think it's very useful and opens a different game market, an alternative to flash (which is also completely downloaded and run by your pc...). Would be great to have an example game in the samples folder.