I like Java a lot, and I used to like applets - what better way to "publish" your game than to stick in in the web page? People can then play it straight away. Okay, it might take a few seconds to get going, but other than that, I used to think it a great idea.
However, I recently installed a new version of Ubuntu, and I just can't get applets to work. Java is running fine, but in Firefox, it doesn't have the Java plugin, and I've tried everything I can think of, even adding symlinks to the Firefox directory. Even if that had worked, no-one should have to do that just to get applets to work.
It shouldn't be this hard. Java should be as easy to install as any other plugin (i.e. incredibly easy). Until it is, it's just going to get even more sidelined over Flash.